Personally, I think there are many more minor side effects with RAI than Drs. will admit. They think all of the minor complaints are just a coincidence.
I had RAI for a hot nodule. A couple of months later I had inflamation inside my mouth. Blood blisters inside my cheeks and under my tongue. My gum tissue got inflamed and it actually felt like my teeth moved apart.
All of it went away on its own. You just have to deal with it.
Meanwhile, keep pushing water! Drink as much as you can to flush out your system. Lemon drops help with the dry mouth too.
Hang in there and give yourself time to heal.
You need to consume lots of water for 6 to 8 weeks after RAI and keep the saliva in high amounts.
Your drying out and that can happen.