It's actually a side effect of Armour. I was having that problem, and complained to the doctor and the idiot tried prescribing me anxiety medication for it.
Look up Hyper thyroid symptoms..anxiety, heart palpatations, nervousness..etc.
Also if you're taking Wellbutrin for depression.... Depression is a low thyroid symptom. If you're having blood tests and the doctors are saying its normal, get a different doctor..preferably an Endo.