In your case, there are a lot of possible causes, so
the question is, how
to figure out
the cause in your case. Do you have a good doc who will work with you on this? If so, just off the top of my head, some good things to check are thyroid hormones, as well as iodine, vitamin D3, and full iron panel including ferritin. You want these levels to be *optimal*, not just "in the normal range".