3 yr old Male cat won't stop spraying/peeing

So, a few months ago, my 3 year old (neutered) Male cat began spraying. When I took him to the vet, they found crystals in his bladder and after a month of taking medication and return check ups, they passed and he was fine. But recently, he's been spraying on the walls of our living room and I haven't the slightly clue as to why. There's aren't any other cats roaming the neighbor (most went missing or were eaten by wild animals), he knows where and how to use his litter box (he'll poop in there but that's about it), when we thought it was maybe something stress related, I took him back to the vet and we put him on some medication to reduce his anxiety (it helped for a week and then he want back to spraying), Feliway doesn't do squat and we've tried taking him outside more (because he'll meow like crazy to go explore outside) and playing with him more. My family is already looking into shelters to take him to, but I've become desperate in finding a solution. Please help!

Mapping: DefaultPageMap
Map Field: TopLeft
Ad Slot: PW1_RON_Top_Left
Size Mappings: Desktop Only
Mapping: DefaultPageMap
Map Field: TopRight
Ad Slot: PW1_RON_Top_Right
Size Mappings: Top_Right
Submit your own photos!
Dog Breeds Selector

Find your perfect match based on activity level, size, intelligence and more!

Mapping: DefaultPageMap
Map Field: BottomRight
Ad Slot: PW1_RON_Btm_Right
Size Mappings: Btm_Right