That is a great question and one that is best answered by your primary care doctor
or other medical provider. Based upon the limited history and physical provided, it is not possible to elucidate the exact cause of this hip pain that you are describing as there is no mention of your age, gender, other medical comorbidities or any other associated conditions, but this is another reason that it is best that you are evaluated by a medical professional as he or she can obtain this information and give you a better idea of the cause of this hip pain. In general terms, one of the most common reasons for hip pain in runners is IT band issues which can usually be alleviated by an adequate stretching routine prior to going for runs. If this is indeed the problem, your doctor may prescribe some stretching options that help you stretch out the IT band prior to running to minimize the pain that you encounter. You may also consider using ice or heat packs, NSAIDs, and compression to the affected area to help with the symptoms as these may also help with the symptoms you are having.