I dont know why but I suggest you take your son to and endocrinologist. does thyroid cancer run in your family? Have they done an ultra sound on his throat. Have they done thyroid blood work? These are all things you need to check out. Make sure if they do an ultra sound and find anything unusual you make sure it does not have blood flow through it a cyst will not have blood flow but a nodule will. I am not trying to scare you but these are things you need to have checked for your sons health. Tyroid cancer does run in my family my mom had it. I had no symptoms and her endocrinologist. insisted i be checked. I had to argue with my doctor to have these test done. Went to an endo on my own I do have a nodule on my thyroid and have to have it check every six months because it is growing. If caught early it can be removed. And you will have no reoccurrence of cancer.
I hope everything goes well for your son and will keep im in thoughts and prayers. Please let me know how everything turns out. If I can answer any more questions please feel free to ask.
Thanks! I'm sure he'll be ok-it's probably nothing at all! I hope you're doing well!