Brown spot on toenail?

I'm a 19 year old guy, and for about two months i've had a small brown spot on the large toenail of my left foot. It's about the size of a pea, and it doesn't hurt at all. At first I thought it was a bruise or something that would go away on its own (although i don't remember injuring my foot), but it still hasn't gone away, and now i'm starting to get worried. I did some research on google and I found something called "toenail melanoma", which really freaked me out. The spot hasn't got bigger or spread or anything, but i'm still going to go see the doctor tomorrow. Anyone know what this is? Please don't scare me...