Do I have melanoma? I have a raised zit like area and I have a mole.?

I just got back from working a summer out at camp, I'm 19. I put my hand on the back of my neck and noticed the king of all zits, it was painful to touch, I promptly went into the bathroom to pop it. It wouldn't pop, and was scarily hard. I freaked out a little, and over the next few days kept trying to convince myself it was a zit, I'm scared that I managed to push whatever it was deeper inside of me because now it is fairly flat, but the skin around it is crusty and red, and there is a very small light brown mole in the very middle. What should I do?