I used to always have hip pain when I ran, even back in high school. But I finally asked a doctor a year or so ago (I'm in my late 40s) and was diagnosed with bursitis. She sent me to a physical therapist, who helped me with exercises to stretch a tendon or something, and it helped a LOT.

Biking doesn't bother it at all (I started biking now after physical therapy, but I biked as a kid, too), and now I can run without it seeming to be bothered, but I haven't run much.

I love the way the physical therapist could help me! Maybe ask your physical therapist for advice for your specific problem?