I ran my first XC race today and around the 2 mile mark I had the urge to throw up. Then with about 3/4 left in the race I started dry heaving. I didn't eat anything before the race all I had was 2 cups of water. This usually happens after my race, not during it. Does anyone know why this is happening and how to prevent it? It really slowed me down because I had to basically run and throw up and the same time. It's very frusturating.