Blood in stool, cramps, 17 years old!

Last summer, I was very underweight and had eating issues. I only had a bowel movement 1-3x a week and sometimes they had blood in them...However, this year I gained a lot of weight and started eating normally, and the blood went away...
This past month though, the blood has come back (about three times this month), accompanied by stomach cramps before passing a movement or after eating. The blood is not a lot, and it is bright red (mixed in with the stool and just a tiny bit on the toilet paper). Also, I have a bowel movement everyday and I don't have to strain..it is somewhat soft and comes out either in pebbles or one 'log'. I have lost weight again but not nearly as much as last year.....My mom is going to call the doctor tomorrow, but I just want to know what you think?!