fingernails falling apart

You should get copies of your labs. Just because a doctor says they are "ok" doesn't mean anything. You could be a point away from deficient (according to lab values) and they'll say you're fine, then by the next set of labs you can be in the crapper.

Last fall, I went in for just a few labs, potassium, D and calcium. I got a call from the NP, that I needed to stop my D ast it was 114 and my calcium was 10.5 (high 10.4). I needed to stop them for a couple of months and retest. I emailed back and asked them to put the labs back in and I'd retest in a week. I stopped my vits for 4 days and retested. My D showed up at 84, and my calcium dropped to 9.5. Can you imagine what my values would have been after 2 months? Me neither.

Educating your PCP and getting your own copies of the your labs are essential. I've kept my spreadsheet for 9 yrs. I was 9 yrs out yesterday. I can no longer bring my iron up with oral supplementation and need infusions now. I do have to take a prescription for Potassium and have from the start. It generally hangs at low 3.5 - 3.8 or down to 3.2.

I get my labs yearly and adjust accordingly. We'll retest if low. I take my A, D, E & K in the middle of the night away from food, and take 25K-A, 50K-D, 400iu-E and K when needed. I've dropped down to calcium 5x/day.

You might want to add Zinc for the nails. I take 2-50mg of zinc per day. I think I need to add another one. If you search in the threads, I think Haley had posted what your nails told about what you were deficient in.