What could a pain in left side, by a woman’s hip indicate. That feels like the cramp you get when run.
Is it in all the diodes down your left side? 
The runner’s “stitch” you mention is thought to be due to lack of oxygen to the muscles. Try to do warm-up stretching & stay well hydrated during exercise. You don’t say where exactly you feel this pain- in a joint, muscle, deep inside? Does it come & go with exertion? Hurt to apply pressure, painful to move the hip joint?
Could be “mittelschmerz,” a fancy-pants name for the pain caused by ovulation. Check the calendar and see when this pain occurs. If you experience it half-way between menstrual periods, and especially if it alternates from one side to another…sounds like “mittelschmerz.”
Try ibuprofen.
~VOW
Could be a cyst; could be endo, could be a lot of things, might be nothing at all. See a doctor to be on the safe side.
Drugs + hot water bottle = degree of comfort 