I Have A Sore On My Leg, Began By Looking

I have a sore on my leg, began by looking like a brown recluse spider bite in October. Scab area is about 1/4 inch in diameter surrounded by a purplish skin color about 2" in diameter. stings and burns like a burn, but it is not fevered. A light rash with itch sometimes surrounds the area. I suffer from varicose veins in that area and am wondering if the slow healing and stinging and burning feeling is due to poor circulation, Took 2 rounds of antibiotics in October. Was allergic to the first, then changed to Amoxicillin. Have treated it with antibiotic creams, anti-itch creams since.