It's kind of doubtful that it has to do with thyroid. The thyroid is a butterfly-shaped gland located just under the Adam's apple. However, sometimes thyroid does cause esoteric symptoms. Unless you've been diagnosed with a thyroid condition or disease, thyroid would not be the first place I'd go on this. What does your doctor have to say?
If you have had RAI it might be an issue with a salivary gland, even with out RAI you could have a salivary glad infected edt... Best to call the dr and see if they want to see you.