Since being on Oxis (for 3 weeks) I have been waking up in the night several times with terrible cramp. It has been much worse than cramp I have had in the past and lasts longer. Then when I get up in the morning I cannot put my weight on my foot. The muscles are painful, sometimes all day. I have also had it in the back of my thigh. Does anyone else have this symptom, and will it settle down. I would like to know why this should happen if anyone knows. Would it be better to change to another drug? I do not want to be taking painkillers for this as well. I am eating more bananas but to no great effect. Any advice welcome.