I would get down to the doctors asap. Trust me, its worth the risk of you telling your mom. If it is cancer (which it might not be), telling your mom and getting it cured is a lot better than dying from it. I know it can be embarrassing, heck i had to tell my mom about a lump on my testicle (turned out to be nothing). If you really feel scared about telling your mom, phone up a consultant or check the NHS website.