Oscar troubles again

I've posted quite a lot in the past about my rescue bun Oscar.

He was neutered a few months ago which all went smoothly and I have found since that he has become a little less hormonal. (with the few exceptions of him biting my sister)

The only thing that i have noticed since his neuter is that his urine really really smells. A lot worse than prior to the op. So much so that even when i'm sat with him out i can tell instantly as soon as he has been back to his litter tray because of the smell!

He lives inside and i clean him out regularly so thats not the issue.

Any ideas on why this is? I could understand if it had always been the case but it hasn't :S

Bump!

I'm sure someone more knowledgable will come along soon but it might be worth checking his scent glands. There's a video on YouTube of how to do it. He might not have cleaned himself properly after his neuter due to being sore so he's got a bit stinky.
I hope this helps.