Ouch!

Does anyone know what causes cramp? Better still, how can it be cured? I've been getting the most horrendous muscle cramps in my right calf over the last couple of days. It all started when I tried to get up off the sofa, whilst pinned down by two snoozing cats. I felt something twist in my leg, and then I had the most excruciating pain I think I've ever felt. Even worse than my stupid arthritis. I shuffled over to the baker's earlier, looking more like a drunken, geriatric yeti than a human being. It's been waking me up at night, too. I think I need to Google cramp, to see if I can find a solution.