Worried Gecko Owner

Hi everyone! I have a 6 year old male leopard gecko who I am very worried about. He is in a 30 gallon enclosure on paper towel bedding, he has a normal humid hide on the warm side of his tank. I keep his hot spot at about 90-92 degrees and his cool end is about 72 degrees. I also feed him a calcium and multi vitamin suplment. He stoped eating for a while and started to loose weight, so I took him to a vet and they found he had plugged pores in his vent which they removed and thought could be the reason for him not eating. They also ran some other tests and found he didn't have parisites or any other issues. They gave him an antibiotic but other then that they said he was in good heath (other then him being underweight) and told me he should start eating again soon. Its been a week since then and he still won't eat. I contacted them again and the gave me a food suplment to give him via a syringe so I have been feeding him that. I'm not really sure what else to do other then wait it out until he starts eating again, but I am super worried. He also has been sleeping a lot more and no longer gets up to greet me when I walk over to his tank. If there is any advice anyone can give me it would be much appreciated!