...diarrhea, nauseous but can't throw up.? My stomach really hurts, I think I have a fever, and I've got horrible diarrhea. I can't throw up but I'm nauseous. I have been sleeping on and off all day to try to get away from it, but I'm still really tired. Yesterday I only had a headache, and now it's come to this. I have been going to the bathroom at least every thirty minutes. I have only had a little to eat today because I thought it would make it worse. Any ideas as to what it could possibly be? I just joined cross country and am supposed to run for twenty minutes today, but I think it will make it even worse than eating. Should I run anyway? Should I go to the doctor? Please help. Thank you so very much!