I have pelvic obquinity, i am a 16 year old girl. why does it act up worse in p.e where i can not do a lot of the excercises with flexibility or run.

See your doctor: Pelvic obliquity can be caused by leg length inequality, contractures about the hips, as part of a structural scoliosis, or as a combination of two or more of these causes. Careful physical and radiologic evaluations are necessary to establish the correct diagnosis. Treatment is then directed toward the specific cause, ie, leg length balancing, release of hip contractures, or scoliosis correction.

You need to see an: Orthopaedic surgeon to assess what is your problem as pelvic obliquity reflects another reason such as unequal leg lengths, a hip problem, a spine issue like scoliosis or muscle tighrening or contracture to name a few.