What to do about my black toe nail?

Trauma or not?: If it was from trauma i.e. You dropped a brick on it causing a black nail..You will eventually get it back, with a new nail of course. If no trauma at all and just started turning dark underneath slowly and growing, i would have it evaluated for possible melanoma..Subungal melanoma, which is quite rare, but happens..Don't mean to scare you, but that is all i got from your question.. Good luck.

See a podiatrist: If you injured the toenail and it is now black, it is probabley from blood under the toenail. If it is painful, you should have the blood drained. It should be looked at by a podiatrist to determine what to do.