I had pain similar to that although mine would flash down and back up the back of my leg at random times. I went to an ortho doc who discovered I had an inflamed disc in my spine. He injected a steroid/pain med into it and I haven't had it since. I did, however, develop a hernia in my groin which causes a similar pain. Can't do anything about it until I get my symptoms under control though. If adding the potassium and magnisium doesn't work, I would suggest an ortho doc.
Good luck! :)