A standard look at causes with thyroid would be to run blood labs and then follow with a US scan.
You need these labs.
TPOab should be >
FREE T4 ( should be mid)
FREE T3 ( should be in the 3/4 high end)
TSH - ( should be between 1-2) for most patients.
Stress these and a full scan
I had the same issues with my salivary gland. In my case it was about 8 months of pain when eating, they tried every antibiotic to no avail. I finally had to have surgery to remove my submandibular gland, they called it chronic sialdentis, along with two enlarged lymph nodes. All was removed & NO PAIN.....
The Dr. said that the CAT scan showed a calcification of a ligament and two lymph nodes. I'm not sure what that means, I have an ENT appointment today....I guess I'll find out more today.