Hi My Daughter Is 13 1/2 Years Old Takes ADHD

Hi my daughter is 13 1/2 years old takes ADHD medication concerta ER 54 mg daily. She has been taking it for almost 2 months .But for the last week when she has had a couple of bowel movement thathave blood and it even is in her underwear. I am making her a dr appt in the am .But wanted to know if I should be very concerned about this problem.