I'm at the end of my tether with cramp. GP said to take a magnesium supplement. I've been doing that for months but it doesn't make any difference. I get really painful cramps about twenty times a day all over my body. For example, I bend down to unlock my bike - cramp in my side. I stretch my arms over my head - cramp in my back. I pull my swimming cap on - cramp in my eyebrows!!! Any stretch or movement is tricky. I know it seems trivial but surely there is something I can do? I have already tried drinking more water.