Infection from the lake?

I'm literally super worried I caught an infection from the lake on Memorial Day. I've been throwing up and shitting my brains out since we got back. I'm going to try and take another shower and some meds...but I feel gross because I feel like I caught something from the lake? Is that possible? Is it from getting a sunburn? Bad food? I have. No. idea. But does anyone have any advice on how to start feeling better? I feel like ass.