[Suze65]

Hi there, sorry to hear your tort isn't well. It sounds like his temps are good, I would keep him warm at night too with a ceramic heat emitter ( not light) for antibiotics to work you need to keep him at 30c 24/7. Is your exotics vet a specialist in tortoises, because this can make all the difference. I wonder if it might be worth an exray to see if he is constipated or has a bladder stone or both, have you noticed him straining, is he passing urine. I'm not sure why the vet is giving him antibiotics if he/she doesn't know what's wrong, if there's not constipation or bladder stone, a blood test might be the next step. Keep up with the warm baths and heat night and day. If he seems worse by tomorrow, I would go back to the vet. What area are you, there are good reptile vets in Bath , Swindon, Andover, and Cardiff .
Diagnosing tortoises can be very difficult, not at all like diagnosing mammals.