For acidity and vomiting, over-the-counter options like Omeprazole (for acid) and Domperidone (for nausea) may provide temporary relief. However, because you also have abdominal pain, it is crucial to avoid self-medicating. These combined symptoms could indicate gastritis, food poisoning, or more serious conditions like appendicitis. Please stay hydrated by taking small, frequent sips of ORS or water, and avoid solid food for a few hours. If your pain is severe, localized, or accompanied by a fever, seek immediate medical attention. Consult a doctor for a proper diagnosis and tailored prescription.