What Causes Dark Brown Skin In The Toes?

Hi, I'm 16 and i need help, about a month or two ago i found a scab on the end of one of my toes when i was in the bath and all i thought to myself was "how did that happen?" then eventually it healed and just turned into dry skin, it was dry skin until around Saturday this week just gone, now it is a very dark, brown circle, it looks a little bit like a mole but it just feels like dry skin, could this be a mole or just a bad dry skin problem, its concerning me.
thanks