Stomach acidity and pain are very common and usually easy to treat. For quick, temporary relief, you can take an over-the-counter antacid containing magnesium hydroxide or calcium carbonate. To reduce acid production longer-term, medications like famotidine (an H2 blocker) or omeprazole (a proton pump inhibitor, taken 30 minutes before your first meal) are highly effective. Meanwhile, try to eat smaller meals and avoid spicy, fatty, or caffeinated foods. If your symptoms are severe, persist for more than a few days, or are accompanied by vomiting or dark stools, please consult a healthcare professional for a proper evaluation. Wish you a speedy recovery!