Bump on Penis Shaft...Help?

I was taking a shower and I noticed a pea size lump on my shaft more towards the sack. I noticed that it itched the day before. Its like under the skin but you can tell its there because it sticks out the size of a pea. I am only 16 and really scared because i dont know what it is. I may add that it is the same color of my and it is somewhat hard.