I was originally on Synthroid. My body did not metabolize it and I was taking a high dose but it was not showing up in my blood work, although I had symptoms of being hyperthyroid.
Can explain this more ? you said that you were on a high dose and you felt hyper, that is normal, since you were over medicated .
Anyway, The brand name you take has a direct influence on how you feel, that is because every brand name has it's own formulation , you might want to ask your doctor to try another brand name like Levoxyl .