I had this condition last week. I found that my have had changed washing powders. My legs started the first night when the bed clothes were changed, I even woke up scratching. This happened also with a new pair of jeans which were the stone washed type. They were like dusty when new with powdery grit still in the cloth and pockets. On the washing powder thing. We ditched the new one and rewashed the bedding. I was nine again from the first night.