I was bit by something on the outside of my left ankle 2 months ago. it stung very bad for about 15 min then itched. yes i did scratch. there was no noticeable sore than or now but the back of my foot is swollen on both sides. it's not red just swollen.

See a doctor: This may or may not be related to your bite, but it does need attention.

Possible bursitis: If the area is swollen to the back of the heel area after trauma, bursitis is a common cause. There is a small bone or projection to the back of the ankle bone that could have broken off-- diagnosis with x-ray, or the possiblity of tendonitis to the area. Best to see your podiatrist to have this checked out.