I am an active 38 year old woman experiencing pain in my calf muscle when I walk, similar to a cramp that doesn t go away. The pain eases when I stop & sit down but doesn t completely go away, I ve had it for about 3 months now & it s really starting to worry me. I m not a couch potato by a long shot, I spend a great deal of the day on my feet for work & walking is essential for the work that I do. I only weigh 45 kilos, I do smoke but not a great deal, I have chronic back pain & take oxycontin for that as well as panadine forte to back it up for really bad days. Can the oxycontin be the reason for the leg cramps or is this a new development connected to my back pain? Or something else again?