Talk to Dermatologist on Blacken Toe Nail

My toe nail has started to turn this color and loosen a bit of its skin underneath and harden nail. Last year meray nail me gaddhay jaisay lines thy but nail grow hotay hotay it ends but ab nail asay blacken ho rha and just now am feeling slightly pain but it’s not permanent not even a sharp pain. What can be the reason and what should i take? Please suggest.