Eira thanks a lot for your input. I am really sorry to hear that you are so stressed. The information given by you is excellent and i can guide you what ideally should be done. I will try to be clear and precise. There are certain risk factors in your case but there are certain goods too. The risk factors are;
1. Age more than 40.
2. Solid nodules on USG scan rather than cystic.
The goods are;
1. The long history of 15 years.
2. Insignificant change in size of thyroid.
3. No associated symptoms which i asked for.
4. Your biopsies were normal always.
So the point is what should be done, here are the important points.
1. You should ask your general surgeon to proceed with surgery and he should do surgery on both sides because nodules are bilateral.
2. He should not wait for 6 months now. This doesn't means that you have cancer but earliest intervention
As far as anaplastic CA is concerned, just forget it, i assure you because that type of carcinoma of thyroid is so aggressive that you cannot stay with that for so many years. You don't have a single symptom associated with it. Your biopsies were always negative so that is not a problem. I give you my words that you should not stress yourself.
Lastly the types of headaches and neck pains you are having are not associated with your thyroid. They can be because of tension or anxiety or related to something else like muscles or spine. Tylenol or ibuprofen should be tried and if symptoms persist, see your PCP for this. But please don't stress yourself for anything life threatening.
I wish you good luck that you get well soon, please ask if you have any question because our discussion always remains open so you can always ask more till you are satisfied, You can click the smiley to rate the answer. You can come back here to ask anything even after you have rated the answer. I will be glad to help you always.