If it's right above your collar bone (not where your Adam's apple would be if you were a guy?), then it's not on your thyroid. You still should see an Ear, Nose, and Throat specialist.

It's probably just a benign cyst or nodule, but you shouldn't ignore it, especially if you are starting to feel it inside your throat. These things can grow to where they obstruct your airway or start to make it difficult to swallow (yes, even benign cysts can grow, so don't panic). The doctor will probably want to biopsy it and get an ultrasound. If everything comes out clean, then they will just want to watch it to see if it gets bigger or smaller.

These things rarely have to do with health or diet, so don't think it's something you did wrong. Again, most of the time these things aren't anything serious. Going to the doctor is just a precaution.