What Causes Nausea Along With Diarrhoea?

Hi Doctor, I have been feeling nauseous with diarrhea for three days. When it first started I had 2 bowel moments that were black and grainy looking like coffee grinds. Now I m feeling like I ve been punched in the left abdomen and there is outward pressure. I felt like I was getting better but now all I want to do is sleep and drink. Very thirsty. My insurance is not so great and I don t want 15 tests run. What could this be?