Hi, The Other Day A Spot On My Back Starting

Hi, the other day a spot on my back starting itching really bad. When I looked at the area, which was right on my spine on my lower back, it had a small red rash. It hurt to scratch so I did not itch it. The next day the area had a very large bruise, which hurts pretty bad now. I don't normally bruise very easily and did nothing to cause a bruise on my back. Is there any reason to be concerned?