FLUTD After Vet Question

My cat was rushed to the vet Sunday night due to not being able to urinate. We were told he had FLUTD and he had a blockage. They catheterized (sp?) him and kept him two nights. Today they took the catheter out and said he was urinating fine and they prescribed a special diet. I got him home and after a bit he went to use the litter box. We have three boxes (multiple cat home). He went in the first box, urinated a tiny bit and got out. A few minutes later he went into the second box, did not urinate at all, but sat there like he was trying...he got out of the box and began cleaning his private area, (this is the exact behavior that made me bring him to the vet in the first place), then a few minutes later he went into the third litter box, urinated a tiny bit got out of the box and cleaned his privates. I'm not sure if this is due to the cathetar being removed, and he's sensitive, or if he got blocked again from the time he left the vet to the time he got home (less than a half hour!). I am trying not to over react. He is on antibiotics and sleepy so he has not tried to use the litter box since I gave him the antibiotics. Any feedback would be great. Thank you in advance and sorry for the spelling errors, to tired to check them now! Thanks again.

I'm moving your thread to the Health and Nutrition forum where those with medical knowledge will be more likely to see it.

It might be good for you to call the vet to see whether he/she thinks there is a problem. I hope he is okay!

Definitely call the vet. Sometimes this behavior is normal for a few days after a blockage, but sometimes the blockage can return. Only your vet can advise whether you should bring your cat back in.