Sounds like something that I have been experiencing....Does it hurt your jaw sometimes? Does it go all the way down to your sternum and radiate to your back?
The AACE recommends to do the thyroid neck check in this case:
Hold the mirror so that you can see the area of your neck just below the Adam's apple and right above the collarbone. This is the general location of your thyroid gland.
Tip your head back, while keeping this view of your neck and thyroid area in your mirror.
Take a drink of water and swallow.
As you swallow, look at your neck. Watch carefully for any bulges, enlargement, protrusions, or unusual appearances in this area when you swallow.
Repeat this process several times.
If you see any bulges, protrusions, lumps or anything that appears unusual, see your doctor right away. You may have an enlarged thyroid, or a thyroid nodule, and your thyroid should be evaluated.
Don't get your Adam's apple confused with your thyroid gland. The Adam's Apple is at the front of your neck, the thyroid is further down, and closer to your collarbone.
The thyroid moves up as you swallow so anything orignated in the thyroid would also move up.
source: thyroid about.com