Hi. I have Hashimoto and I experienced what your describing during my hyper phase. Are you feeling hotter than normal? That was another thing I had. Have you had your levels checked yet? If you do have them check your thyroid antibodies. I had symptoms for about a year before my thyroid levels went out of whack.
I was diagnosed hypothyroid in January 05. Nausea was one of my BIGGEST symptoms. That and the mantal effects (anxiety, depression, derealization). I think most of it was because of the toxic stage of thyroiditis but I still experience the syptoms today. I have good days and bad. They seem to last in spells of about 4 days. My dosage of Levoxl is still being adjusted (Im at 75mcg now from 125 a couple months ago). I have been put on Zoloft for the past few months too. The anxiety from the thyroid disease could be causing some of the nasea. I seem to feel better everytime my Zoloft dosage goes up(Im at 75mg now) but then my simptoms of nausea and anxiety seem to creep back a bit. I dont have the solotion yet but I do know that the tyroid can be the cause of some major symptoms all over the body and mind. I hope you feel better soon. Good Luck!