A few months ago I have notice bumps appear on my upper back. They are really itchy and are dark colored, since they have started they have spread to the backs of my arms and farther down on my back. The bumps are so itchy I scratch at them causing them to bleed and now my back is really sensitive, especially when I get in the shower it hurts when water touches it. Does anybody have a clue what's going on or how to treat it?

I'd see a dermatologist.we can't possibly know the cause or the treatment.