Update. Gizmo went to the vet yesterday. This vet said it is possible for the hyperthyroidism to come back. She said usually some medicine for it will straighten it out. She, however, does not think it is the thyroid that is the problem. She felt it during the exam and didn't find anything to worry about. She believes it is a gum infection and prescribed an antibiotic that is made just for this problem. She is putting him on a "pulse" treatment. This means 5 days of the antibiotic, once a month, every month for now. She had me sign a release to get the results of his blood work from the other vet. She doesn't feel it's necessary to make him go through that again and to save me money!
She said he still has all his teeth and at his age she wouldn't want him to have a dental cleaning. Yippee! I think I really like this vet. She's looking out for him, and not treating me like a walking ATM! So, I'm keeping my fingers crossed that this works for him.
I really want to keep this vet. I felt such a positive vibe at her office. They even have cats roaming around inside that belong to the office. These cats were unadoptable due to their "attitudes" so now they have a forever home. I'm such a sucker for things like this!