I Have Red Splotches That Has Been Reoccurring On My

I have red splotches that has been reoccurring on my left arm for several months. They start out itching and then after a few days the itching stops. It has been getting worse as time goes on. I am now starting to notice the spots appearing on my legs. My family doctor looked at it and didn't know what it was. He prescribed some steroids to help with the itch. Any thoughts?