Hi - Longtime Hashi's patient here (20+ years). Because it's auto-immune, during the early stages, the thyroid can "storm," meaning that it will have periods of producing large amounts of hormone and other periods of producing very little. You may want to ask your doctor to recheck again in a couple of weeks to see if your levels change. I can't say for sure that it's not related to tumors, but from what I was told when I asked that question, it's fairly rare.

I assume that they actually found antibodies in your bloodwork and that's how you know it's Hashimotos? If not, they maybe need to do some testing for other conditions as well, as it would be unusual to be hyperthyroid and that tired, although it is possible depending on what else is going on with your body.

Hoping that you are able to figure it out and start feeling better soon. I know what that feels like and it's definitely not fun.