I went hiking about two weeks ago and decided to lay on some rocks near a waterfall. I got a whole bunch of bites on my legs, but they all went away except for one on my thigh. I assumed that the rest of them were mosquito bites except for that one. The bite on my thigh has a dry peeling patch in the middle and the skin around it is hard and purple/blue. i think the purple skin is slowly getting bigger, but what could i have been bitten by?