in neck can affect your salivary glands and this may lead to increased salivation, medications can cause metallic taste
. These are unrelated to thyroid. Since you are a male and you had a radiation in neck you are at risk of thyroid cancer
. So if you have a goiter and symptoms like difficulty in swallowing or tlking you should have it evaluated.
If i was your treating physician I would have done the following tests
Thyroid function test, Ultrasound
of Neck , FNAC (Needle testing) of thyroid
If investigations show any doubt i would suggest you surgical removal of your thyroid.
Hope I have answered your query. If you have any further questions I will be happy to help.
With warm regards,
Dr Ajish TP (MD,DM)