Pain coming on after a run means a more inflammatory response rather than purely mechanical. It suggests a more chronic condition, that could still be only muscular, but could also mean tendoniosis or joint ligament damage, which is associated with 'achy' pains and stiffness after sitting a long time or first thing in morning. Intial treatment in this case is pretty much the same as muscle treatment (stretching) but generally will take longer to clear up and you have to be more careful with rehab exercises and increasing load through the hips (to prevent flare-up). Sharper type pain could suggest more neurological or joint cartilage issue, which may resolve with soft tissue work and mobilisation from sports physio. IF your pain is more or less constant, depending on severity of symptoms there maybe more serious underlying condition but, of course, if you have a constant high level of pain, you should be speaking to your doctor.