What Causes Red Spots, Swelling And Soreness In Foot And Leg?

I was diagnosed with Lupus 30 yrs ago. It was under control all this time. Now I have some symptoms again. I had Knee replacement in Oct. After that I had red spots and a swollen fore foot and up half my leg. I have been treating it with Epson Salt and elevating it, but it does not help. Me leg looks just like 30yrs ago. My primary care physician does not believe me that I have Lupus. My Daughter also has it. Should I go to an Internist and get some tests run? I am 75yrs. old.