Dave is doing great. he has been back in vets today as he hadn't pooed, but vet decide to leave him a couple of days. Dave then then decided to leave me a smellie present in the cat carrier on the way home.
He is weeing well, not quite aswell as before this, but enough to stop his bladder getting dangerously full. The bladder wall linning has decreased in thickness which is great news and it is now less tender, which is also good news.
Behaviour is back to normal.
I am so glad to have my wonderful boy home.
Thank you everyone for all your kind words and very helpful information. it is all very appreciated.