Severe stomach pain with vomiting and slight fever is usually due to a stomach infection or food-related illness affecting the gut. Take proper rest, drink small, frequent fluids, eat light foods like rice or banana, and avoid oily or heavy meals to help recovery. Keep yourself hydrated, monitor your temperature, and avoid taking multiple medicines on your own. If pain is severe, vomiting continues, or fever increases, consult a doctor for proper evaluation and care.