Numbness on the left side of my body?

I know it's not a stroke or anything like that, but on one side of my body, sometimes it switches, I get slightly chilly on either side. I also get incredibly itchy and sometimes I have patches on my back that burns. I am also very sensitive and sometimes my left hand goes very cold and numb. It only happens when I'm anxious and depressed, not when I'm feeling positive and better. What could it be?