About a week ago, I had (what I thought at the time) a mosquito bite above the back of my knee/ lower thigh, over the course of the week it has continued to itch (not an intense itch) and has gotten worse. Now it has developed into a large red, circular rash with a s-shaped lined spreading from it. my husband thinks it look like a worm and now he has me scared! Is this fungal or should I be going into the hospital for something more serious??