I am going on holiday to India for 6 days and was wondering if anyone knew of any form of preventative medication which I would be able to acquire in order to try and stop some myself getting some of the local bugs.
I would suggest visiting your GP and ask their advice. Here in Australia, every Clinic has list of medicines or shots to be taken before travelling to particular countries.
Also prevention is better than cure. I would suggest avoid eating spicy street food and water. Get distilled or purified water bottle and carry it with you.
Stay in a clean hotel (unless you are staying at someone's home, which would be fine).
Don't be shy to say no if someone offers you to eat or drink something that you are unsure of and you will be fine.
Consider asking your doctor to prescribe you some anti-nauseates. You probably wouldn't even have to go into your phobia with your doctor-- when I traveled to Southeast Asia recently, my doctor automatically forced on me prescriptions for antibiotics and anti-diarrheal medication. (You might be encouraged to hear that I neither filled nor needed either.)
Googling reveals that there are several classes of anti-nauseate drugs. I've taken meclizine (brand name: Antivert) and promethazine (Phenergan) and both were effective-- though they pretty much knocked me out. Even if you end up not taking them, it might comfort you to have them on the trip.
I guess all you need to be mindful of, is basically the food that you will eat. Below are very effective preventive measures that you might want to read for safety: 1. Avoid eating foods or drinking beverages purchased from street vendors or other establishments where unhygienic conditions are present. 2. Avoid eating raw or under cooked meat and seafood. 3. Avoid eating raw fruits and vegetables unless you peeled them. 4. Make sure to buy only safe beverages which includes bottled carbonated beverages, beer, wine, and water boiled or appropriately treated with iodine or chlorine.
I hope this helps.