My 13yo constantly complains "stomach hurts." daily bowel movements but says feels like she has to keep pooping more but nothing comes out. any ideas?

Sure...: This is a common complaint at her age, but the differential diagnosis is quite broad and evaluation is key to distinguishing a functional process versus an inflammatory one (e.g. Crohn's), malabsorption (e.g. celiac sprue), maldigestion, infection, etc. Time to discuss her condition with her pediatrician, who may elect to refer your child to a gastroenterology specialist.