What Causes Blood Blisters On Arms,back And Shoulders?

I have blood blisters, about the size of a drop of water all over my torso.. front and back, and on the tops of my arms and shoulders. They are unbelivably itchy and they have bruises around them. I apparently am scratching hard in my sleep as well. I also have a few that a bit bigger and one popped and dry red came out along with a piece of light brown dry skin. I bathe every 2 days, (cause I have eczema), and I use body butter. What might I have and how do I get rid of it. It hurts, it's annoying and it's unsightly Thanks!