One of my friends was exposed to some kind of toxic metallic dust from working on a boat propeller and apparently it really messed up his thyroid -- He was running around with a hair-trigger temper and moods and anger totally out of proportion to what was going on -- Took them a while to figure it out -- They did some radioactive seed implants to kill his thyroid, then adjusted his synthroid meds until they got it right and he is now just fine.

If you think it's the thyroid meds then get yourself right back to the Doc that prescribed them and tell him/her your symptoms -- You won't get it right until you do that.

I've never had headaches from synthroid and I've been taking it in a number of doses for about 15 years.