Yes, been there . . done that. I had RAI the first time 3 1/2 years ago and then again in January this year. Like you, I had to keep lowering the dosage. The doctor where I live said there wasn’t a problem so I went to Mayo and got a second opinion. After testing, they suggested I take a second treatment of RAI. I’m now taking a higher dose of T4 and they still are unable to get it balanced out. They increase me to .150 so that the TSH responds, but that puts my T4 above the normal range which gives me hyper symptoms. Basically, what I’m doing now is educating myself. I wish I’d done this in the beginning but I guess I was blind & trusting. What I’ve learned is, with myself, it’s the stupid T4/T3 conversion that gets to be a pain in the butt. It just doesn’t seem to be as efficient with me as the drug makers claim. Don’t mean to be negative about this, I’m just frustrated and letting off some steam.
If I can help you with anymore information, let me know.