I was bitten on the ankle by a spider. He got away in the grass so I don't know what kind he was. Pain started right away and didn't quit for days. Iwent to the hospital and the doctor didn't know what to do. No treatment at all. The bite looked exactly like your photo. As I was leaving the doctors waiting room, a lady ask to see the bite. She said a spider bit her mother and it looked like my bite and took a month to heal. I called the Poison
Control Center and they didn't know what to do either.
The second time I was bitten I went to the doctor right away. It was in Guatamala. He said go home and sit on the side of the bathtub and wash it with soapy water. Don't scrub hard or irritate the skin and don't let the waste water splash on other parts of your body. It worked. By the second day it was almost gone.