Had Metal Plate Removed From Ankle. Related To Sciatic Nerve. Why Back Pain And Stiffness In Often?

Had metal plate removed from right ankle Nov 2010 hoping removal and clean up would solve problems, if not at least a MRI could be done in the future hopefully revealing any problems. Unfortunately march 2012 I slipped and had severe back problems which eventually led approx 12 weeks later to emergency surgery on back to trim disc and relieve pain. This was unsuccessful and I returned 7 days later for same op. Since op every 6 to 8 weeks I have experienced sudden pain which is initially like a sprained ankle for the first hour but quickly to severe pain and I cannot walk or put any weight on foot as though I had a broken foot. This would normally be the right ankle which was the one with the plate. It switches on and off like a tap fine on a sunday, cannot walk Monday, Tuesday not too bad and back to the gy on wednesday. It is very difficult to understand. I believe this is all related to sciatic nerve and on the last two occasions it has been the left foot as though I had a ruptured achilles., again it last for a day or two. Recently more back pain and stiffness with a lot of crunching. Any help advice greatly appreciated, this is seriously changing my life. I am 51 years of age and dont want this for the rest of my life. regards garry watson