Does he go outside?
Any blood in the urine?
Is he drinking a lot of water and peeing a lot?
Does he poop in his litter box ok?
Any changes in appetite?
1) no, he doesn't go outside and is never around other animals.
2) no blood in the urine
3) yes, he's drinking a lot of water
4) yes, he's pooping in his litter box
4) he seems to be eating-I've been trying to pay attention to this and from what i can tell, he's eating.
Thank you for the extra information.
he does need a vet exam. I think the two problems of peeing outside the litter box and the sneezing are separate issues. Peeing outside the litter box and drinking a lot of water can be symptoms of diabetes, thyroid problems, or kidney disease. It is possible though he may just have a UTI.
The sneezing can be from many things. Anything from a URI, allergies, dental issues, nasal polyps, etc. You can try to give him a 1/4 tablet of Chlor-Trimeton twice daily to help the sneezing. This is a safe to use OTC antihistamine. If it is allergy or URI it will help.
As for the peeing, that really needs to be diagnosed by your vet for proper treatment. Adding a litter box in the house can help and cleaning the areas he has peed on with an enzyme oder eliminating cleaner like Natures Miracle. But do get him a check up to rule out any serious issues.