Help! Bleeding down there...WHY?

Hi, I am eleven years old and have a pretty good health history and I don't get sick very often. I didn't p bowel movements for a week or so, and I told my mom. A day later I finally went just a tiny bit. It's been three days since I've ped a bowel. Finally, just now, I went. This is gross, but I couldn't go so I stuck toilet paper on my finger and put it up my . I took it out and there was a big amount of blood. I repeated the process and showed my mom. Then, I went a couple pebbles of bowel movement, and there was blood. She said she wasn't too concerned. I kept trying to go and it was painful. I don't think I got all my bowel out, but now my feels really swollen and it really hurts. It almost feels like it's "tight." There was also some dark mucus in my bowel. I didn't eat anything out of the ordinary. I looked at my on the inside in the mirror and there are three giant red swollen lumps inside. My mom said they are hemorrhoids and was puzzled because she never heard of a child getting one. She bought me some cream but i'm still on the toilet for hours and hours in bouts of pain. I have anxiety and don't feel comfortable with a doctor looking in there. What should I do? Could it be something other then a hemorrhoid? What could it be?