My toe nail has been bruised for nearly 3 months. what else could cause a bruised appearance?

Black toe nail: The only serious problem you could have, that gives a black toe nail, would be a malignant melanoma on the nail bed beneath the nail. A bruised nail turns red, and then dark, and then resolves after a period of time, as the nail grows out. It may take more than 3 months for a bruised big toe nail to grow out, so it may pay to be patient and wait, or visit a dermatologist right away for help.

Toe nail: Toe nail bruising can be seen quite often in long distance runners who impact the toe against the tip of the running shoe. Often seen in marathon runners. A blackish singular line in a toe nail should be evaluated by a dermatologist for melanoma.