Have been nauseous for a few days on and off. discomfort under left rib cage. vomited twice. any advice?

Nausea,vomiting: This could be due to gastritis which is an inflammation of the lining of the stomach. Pancreatic pathology is another possibility. Try omitting alcohol,caffeine,nicotine, aspirin or anti-inflammatory medications like ibuprofen or naproxen. Take omeprazole as directed. Ginger for nausea. If no improvement within a week or if symptoms worsen, see a physician or gastroenterologist for evaluation.