Good for you for getting it checked out. I hope it heals quickly. Make sure you take some probiotics too.

I had cellulitis from an insect bite some years ago. The red area on my leg wasn't as big as yours, but it was up on my thigh close to lymph nodes which is not a good thing. A guy I worked with got it from a cat bite and needed to use IV antibiotics for it. It is definitely not something to be messed with.