Hi Anya,
Welcome to our community!! I agree with what Opugirl has said, but I wanted to add that the Endo doesn't have a clue about
his own field, he shouldn't be handing out recommendations about
Lyme disease!
Low TSH is always something that should be careful followed up on. It's one indicator that you have a low functioning thyroid and possible Hashimoto's thyroiditis, especially if Lyme disease is a possibility.
Here is a link to a site that I learned a whole lot about
not only the thyroid and it's real functions, but adrenals and how they figure into it all too:
www.stopthethyroidmadness.com/