What could cause strange pain on the lilac crest?

Iliac crest pain: Several possiblities:adhesions/scar tissue, tight muscles which attach to the crest, minor tendon tears along the crest, pelvic shearing which causes abnormal pelvic functn and thus abnormal muscle/ligament tensions, lumbar vertebral dysf, quadratus lumborum muscle imbalance & more.A good history & phys incl osteopathic hands-on exam should shed light on cause & osteopathic manipulation may fix it.

Lots: This is a common site of referred pain. Without more information, it is hard to answer. Common things include trauma, back/disc issues, fascial tightness, bursitis. Seek out a well-qualified osteopath.