I had similar problem few years back, it went on for months on and off. Eventually I was referred to hospital, had scans which showed pain was worse when I was ovulating. I then had an exploratory camera to check inside and outside the fallopian tubes. There was slight inflammation but nothing major. The consultant started suggesting that sometimes using pain killers can cause constipation which causes lower back pain. I was not happy, I had at times been close to passing out. However willing to try anything, I drank more water and bought fibogel, a natural sphagnum wheat husk, and the pain went after that. Now when I have pain I up my fibre in my diet and drink more. No one was more shocked than me that it could cause such pelvic pain. My groin used to be red hot and I was in agony. Don't use to many pks they can make things worse. Try voltarol rub. Hope you feel better soon.