red rash?

I have had red spots on the lower part of my legs for about four years. Just red spots, they did not itch. I am very fair and have lots of allergies. My dermatologist said they were harmless and use a lotion daily that had cerimides in it, such as Cetaphil. About two weeks ago I got a very red rash, or red spots all over the lower part of my legs and it does itch this time. It has spread a little to the tops of my feet. I am using chickweed salve for the second day and it has helped the itching. I am also using red light therapy, just the second day also. What do you think this rash is? I have had dermatitis before, but not like this.