I am experiencing nausea (severity: severe) . the following also describe me: vomiting and diarrhea. what should i do?

Gastroenteritis.: This sounds like acute gastroenteritis - nausea, vomiting, diarrhea, abdominal pains, fever, chills and sweats are all possible components of this. Could be viral or food-borne, perhaps something you ate last night that may have been undercooked or mishandled. Typically lasts 3-5 days. If it gets much worse, or if it lasts longer than that, see a doctor. Just drink fluids and rest.