Did I pull a muscle or is it an infection in the gland in my hip?

I woke up Sunday morning and I was hurting in my hip like something was swollen in there (alot of pressure). I just started my menstral cycle so I thought it was just girl stuff, nothing serious. Now, this has been going on for 8 days. I went to the hospital 2 days ago and they ruled out apex, ovaries, kidneys, bladder, and all blood work and urine came back good. Then I stared noticing the gland swollen yesterday inbetween my hip and pelvis. It sends a jolt from that gland to my knee everytime I move. I try to straight it, it feels good till I stop, then it just starts back hurting.