What is the cause of awful sharp stomach pain?

Spasm of stom wall. Firmness, spasm, pain of any part of the gut/ gastrointestinal tract is caused by the muscular part of the gut going into spasm, either due to irritation from some food, too much acid, or obstruction of normal movement (peristalsis). If persists more than few days, or fever, vomiting, doubled over in pain occurs, see physician. May try stopping alcohol, caffeine, hot spicy foods, tomatoes 1st.