Spider Bite?

I had went swimming in a nearby pond with family/friends [northeastern PA] and I had been bitten by something. I at first thought I had been stung by a bee because of the reaction -- within literally 30-60 seconds it puffed in a dime-sized area and was white with a red center -- but I was in the water/at the water's edge when it happened and I had seen no bees. I'm also not allergic to them, so when I get stung, it gets a little red and that's it.

I wouldn't immediately jump to the idea of a spider bite because few stay so close to water, but it had two side by side marks, both very symmetrical and round. It immediately burned and the burning was very extreme. Over the course of a couple days it had swollen to almost the size of half my fist [it's located on my hip]. It was very hot and my skin almost felt hard when I ran my hand over it for about an inch wide and two inches long, to the right of the bite. The redness spread about 3" in radius out from the bite.

It's now been about 9-10 days and it's not longer red, hot, itchy, or hard in the area like it was, although it has left my skin purple and sort of rough where it was.

Does anyone know what kind of spider this was, or if not a spider, what type of insect it was? I'm not worried now that it's gone other than the discoloration, but I would like to know what it was out of curiosity.