Any of the doctors can, at your request, order the blood tests to check on your hormone levels. Even low normal is something that can cause fatigue, and as time goes by from the point of treatment, the chance to go hypo thyroid continues to increase. I was good for the first couple of years, and then things began to tank. Annual blood work checking this stuff for people with H&N radiation should be the norm.

Too many institutions and doctors want to let you go after primary Tx is done. You will continue to have issues, and need to find a "gatekeeper" doctor that will monitor lots of things that go bump in the night for years to come. It is surprising how many of your primary people are not up to speed on the long term issues that are consequences of treatment. And since most of these are not life threatening, they are not that concerned about them. Unfortunately your QOL is significantly impacted by all these things.

You have to begin to be your own advocate for screenings, monitoring, and more from now on. Your original team may not be the people that handle you for the rest of your life. While I copy my docs at MDACC with all my scans etc., I have an internist that I trust locally (and who trusts me with the things that I bring to her) that orders all my tests, prescribes Rx's for blood work, supplementation for hormones, scans and more.

Vitamin supplementation is likely not your issue.