During bowel movement today, i had very hard stool and then had blood on toilet paper (not just one tiny spot like other times). i have psoriasis on anus area. and i think hard stool could cut my skin either eternal or external.should i worry?

Old vs. new issues: Blood in the stool, trouble pooping, a lump at the anus, or anal rashes are symptoms that need to be evaluated by a primary care doctor or a gastrointestinal specialist. The cause can be a hemorrhoid, an anal fissure, an infection, etc... Cancer in that area would be ultra rare in a teen. If the cause is already known by the doctor, a teen can just follow her doctor's care instructions.