My toenail has grown back strange. a mound of skin-like material is growing out of the nail bed. so the toe nail grows up and over the mound.

Toe bone injury.: It sounds as though that "mound of skin" may be the result of injuring the toe bone just under the nail bed. Occasionally, the bone, when injured responds by a sudden growth spurt. As it grows upward, it raises the nail bed up and can cause a nail distortion as you have described. An r-ray will usually confirm the event. The treatment involves removing the boney spur. Known as subungual exostosis.