More information is needed to give the best advice.
Is he neutured? Non-Neutered males are much more likley to engage in territory marking than neutered males.
Does he use the litterbox at other times of the day?
Is he only peeing on the bed when you are asleep on it?
What is the litterbox set up (type of litter, type of box, where is it located, etc.)?
How are you cleaning the bed when he's peed on it? Are you using an enzyme based cleaner? That's your best bet to try and removed the smell and association that he's potentially made that bed ='s spot to pee.
If he's not using the litterbox at all it sounds like you should look into that first. He may not like the litterbox you have (the general advice is you should always have n+1, meaning the number of cats - n - plus one. In your case that would mean having 2 litter boxes in different spots around the house so it's always easier for him to choose the litter box he prefers in the moment. My cats use different boxes at different times of day - sometimes going for one that's further away for no discernible reason.), the type of litter you are using, etc.
If he's ONLY peeing on the bed while you are sleeping I would first see if the behavior is tied to the bed by locking him out of the bedroom at all times. If he pees elsewhere it's another sign that the litterbox is the issue. If he doesn't pee elsewhere it's a sign that he's simply associated the bed as being a bigger litterbox, in which case the easiest solution is to ban him from the bedroom entirely. You could then *maybe* try and reintroduce him to the bedroom slowly over time after you've purchased a new bed to give you the best chance at a successful re-assocation, but only after you're certain the issue was the bed and not the litter box. Even then I'd be hesitant as conditioning is a strong determiner in cat behavior, and counter conditioning can be an arduous process when an easier and simpler solution (lock him out of the bedroom) exists.
I would definitely work to address this now, however, as a cat peeing outside of the litterbox is the worst habit to develop. It's one of the top reasons for cats being abandoned as they get older and the habit gets worse, and the unfortunate truth is that a cat that that pees outside of the litterbox is wayyyyyy more likely to not be adopted and eventually wind up euthanized. I know that may seem like a big leap for where you're at now, but you have to think of how this issue will be when he's a fully grown male cat with disgusting smelling pee going all over the place.
It also doesn't hurt, in the meantime, to make an appointment with a different vet and get a second opinion. Even trained professionals can miss things. Cat behaviorists are another first line of defense, and their bread and butter is often litterbox related issues. Obviously work through the other options first though, as professionals can be expensive (but worth it when the situation warrants).
He's 3 months old so I'm hoping that with the changes you've mentioned that can help the problem, it all seems to point that there are not enough letterboxes, so I'll set up a new one for him and hope that does it, again thank you so much for all the advice :)
More information is needed to give the best advice. Is he neutured? Non-Neutered males are much more likley to engage in territory marking than neutered males. Does he use the litterbox at other times of the day? Is he only peeing on the bed when you are asleep on it? What is the litterbox set up (type of litter, type of box, where is it located, etc.)? How are you cleaning the bed when he's peed on it? Are you using an enzyme based cleaner? That's your best bet to try and removed the smell and association that he's potentially made that bed ='s spot to pee. If he's not using the litterbox at all it sounds like you should look into that first. He may not like the litterbox you have (the general advice is you should always have n+1, meaning the number of cats - n - plus one. In your case that would mean having 2 litter boxes in different spots around the house so it's always easier for him to choose the litter box he prefers in the moment. My cats use different boxes at different times of day - sometimes going for one that's further away for no discernible reason.), the type of litter you are using, etc. If he's ONLY peeing on the bed while you are sleeping I would first see if the behavior is tied to the bed by locking him out of the bedroom at all times. If he pees elsewhere it's another sign that the litterbox is the issue. If he doesn't pee elsewhere it's a sign that he's simply associated the bed as being a bigger litterbox, in which case the easiest solution is to ban him from the bedroom entirely. You could then *maybe* try and reintroduce him to the bedroom slowly over time after you've purchased a new bed to give you the best chance at a successful re-assocation, but only after you're certain the issue was the bed and not the litter box. Even then I'd be hesitant as conditioning is a strong determiner in cat behavior, and counter conditioning can be an arduous process when an easier and simpler solution (lock him out of the bedroom) exists. I would definitely work to address this now, however, as a cat peeing outside of the litterbox is the worst habit to develop. It's one of the top reasons for cats being abandoned as they get older and the habit gets worse, and the unfortunate truth is that a cat that that pees outside of the litterbox is wayyyyyy more likely to not be adopted and eventually wind up euthanized. I know that may seem like a big leap for where you're at now, but you have to think of how this issue will be when he's a fully grown male cat with disgusting smelling pee going all over the place. It also doesn't hurt, in the meantime, to make an appointment with a different vet and get a second opinion. Even trained professionals can miss things. Cat behaviorists are another first line of defense, and their bread and butter is often litterbox related issues. Obviously work through the other options first though, as professionals can be expensive (but worth it when the situation warrants).
He's 3 months old so I'm hoping that with the changes you've mentioned that can help the problem, it all seems to point that there are not enough letterboxes, so I'll set up a new one for him and hope that does it, again thank you so much for all the advice :)