This forum is for general pet health questions, such as questions about medications, parasites, vaccines, infectious diseases, breed specific and genetic problems.
I recommend veterinary examination, recheck labwork and fecal examination for parasites. If he is on adequate thyroid supplementation, then he should not be 25# overweight, so a 4-6 hour post pill thyroid level should be checked to make sure it is in the high normal range after a pill. If all the labwork is normal, then I suggest trying a hypoallergenic diet for possible food allergy--I have the best success with Royal Canin rabbit/potato. For his bad breath, he may need a dental cleaning +/- extractions of any infected teeth and then daily tooth brushing after the dental cleaning.
Has your pet ever swallowed your prescription medicine? Vet tech Thomas Dock explores the top 10 meds that harm pets and what you can do to prevent a tragedy from happening.