Suggest Treatment For Cough With Pelvic Joint Pain And Knee Pain

I have had severe cough for past two weeks. This seems to have brought pain in my left side of pelvic joint leading to sustained pain in my thigh and leg muscles. There is numbness in one part of the leg muscle and the toe area in the feet. I have been taking mobizox tablets as prescribed by a doctor for about 4 days but yet to see much relief. Xrays of pelvis and chest do not seem to reveal anything problem. The moment I cough I could feel some pain in my pelvis and down to my knee joint on the left leg. What should I do?