Iron deficiency

So when I had my glucose test 1st one they told me I was slightly anemic and she gave me prescription for iron pills, I haven't started taking them yet but now my nails are lifting up off the nail bed and I have had headaches a lot anyone experience any of this? Also if yes was wondering how long it takes for iron pills to kick in? And if there is anything I could put on my nails to help them heal and become stronger???