Hip pain could be several different things,including muscular tightness. After a year of inactivity, when I began walk/running again, I had hip pain because my hip flexors were so tight. Physical therapy and stretching helped a lot!
Hip pain can be caused by bursitis, which is an inflammation of the fluid sacs that cushion joints. Repeated movements and pressures can aggravate the bursa found in hip joints, causing slight pain while running.
If you have problem in your hip joints gone unnoticed, the pain may occur, what ever work you do.Some time running after a heavy manual work too cause pain in hip region.Another reason is,the joints becoming too tight to show movement. after delivery this pain may come.