Severe nausea and fatigue during and after running??

I always feel very strange because I can do zumba for 2 hours but I can never run. The classes that I do are no less intense than running and definitely get me my cardio, but I never feel sick at all.
I start running and everything is dandy, my pace is ok, everything's great, and then, as any normal human being, I get tired. I push through because I know I can do it, I KNOW I can run without getting sick. Soon enough, I start feeling like my stomach is trying its damndest to make its way out of my body and I know I should stop, so I do so and walk. After a few minutes, my body feels awful. I'm overheating even though its 40 degrees outside and I'm in shorts and I feel as though I'm going to throw up. Even walking is painful and sitting is even worse.
I've run after big meals, small meals, no meals, what have you before and this didn't start happening until.... one day. It was like a switch flipped. I -always- stay hydrated, especially during my runs.
This also sometimes happens when I do blocking drills in volleyball, which is just jumping for a few minutes on end
I've exhausted all the possible reasons and I've tried everything to get it to stop. Nothing works, not eating, eating, drinking more water, drinking less water, more sleep, less sleep, stretching, no stretching.... I'm coming up empty

This is getting really sad, I used to be able to do more than 2 miles 4 times a week and now I can barely do a lap (1/4 mile) without this happening. I never stopped running, so that can't be it either. I was hoping you guys had some ideas... Please help ;-;