Rash/Bug Bite/Blood Clot on Foot? From.

Three days ago I was finding it difficult to put any weight on my left foot. I was feeling a deep ache/pain from the sole of my foot to my ankle. I did not sustain any injury to my ankle or foot that I could think of. The second day I did not notice any irritation whatsoever. On the third day I noticed a strange rash, almost a perfect circle, on the side and sole of my left foot after experiencing difficulty in putting weight on that foot again. The red skin was warm to the touch, hurt, and was slightly itchy. Today, I am able to walk again without problem, but the rash appears to have spread further, looking less like a circle. It is quite itchy today and only hurts when I press deeply on it. My parents are concerned that it may be a blood clot. I am more inclined to believe it could be contact dermatitis or a spider bite. The joint pain could be attributed to Ehlers-Danlos syndrome, which I suffer from.