I think I may have a hemorrhoid?

I'm sixteen years old, and I just recently noticed a lump near my anus. It's not on the surface of the skin, but like a lump inside it. It doesn't itch or anything, but I can feel it. I run a lot, though I have recently been on my break, and I eat a lot of whole grains. I'm just wondering how I could have gotten this hemorrhoid or whatever it may be? I mean, I've gained a couple pounds, but not anything major. And even though it's embarrassing, I should probably still go to the doctor, right?