If you are headed to South India, you may prepare your GI tract for the trip by eating yogurt each day, preferably organic with active cultures, a month before your trip. Eat very little, just enough to stay alive, while you are travelling in India and then only vegetarian food prepared in an Iyengar or Iyer Mess if you are unable to have food arranged otherwise. Do not eat in restaurants or hotels. Stay away from bottled water, juices and soft drinks. Take fresh coconut water, boiled drinks such as coffee, tea, rasam. If you can, keep your diet to idly, upma, pongal, rice and hot sambhar with side dishes of freshly cooked vegetables. Avoid all chutneys as they are prepared with water. Stay away from train food and beverages. Avoid fried food, snacks and sweets. Know beforehand how you will handle the receiving of prasadam in the Temple. If you accept it in your hand you must consume it or creatively apply it to your head without offending others. Take over the counter anti diarrhea medication with you, such as Immodium. Read and follow all package information and instructions. Wash your hands well with soap and water frequently and discreetly use your handerkerchief to to open and close all doors. Most of the germs that cause the diarrhea you are getting are from surfaces you touch and then transfer to your own mouth. Check with your insurance company if they will cover illnesses treated abroad. If so, take your health insurance card with you. If you need medical attention get it from a private hospital. You have a better chance of your insurance company paying some or all of the costs of treatment. Good Luck to you.