We've all been there! You feel a little twinge and you start looking around for the closest loo. Is it just a minor cramp? A bit of wind? Or are you going to be running to the toilet for days? No-one knows! Spend enough time in Bali and it will get you eventually.
Travel anywhere in the world and you're likely to get sick...you've grown up getting used to different bacteria; it makes sense that your body isn't sure what to do with foreign bugs. There isn't a lot you can can do, and I always urge visitors not be scared of it. Gastro probably won't kill you - it's just an unpleasant way to lose a few kilos. I've listed some options for trying to avoid getting sick, and what to do if it happens.
Symptoms
Travellers diarrhoea strikes quickly and usually starts with stomach cramps. You might also get nausea, aching muscles, headaches and a slight fever.
How to avoid it
Luck. I know people who won't touch anything without a hand sanitiser, and refuse to eat the amazing food you get on the street or in local warungs, and yet still get sick! But actually you are more likely to get a bug from a salad at a nice hotel or restaurant.
My place has bore water so I'm relaxed about water from the tap at home (although I don't actually drink it), but town water is problematic so if you are staying in a built up area use bottled water to brush you teeth. You are going to want to shower - we are in the tropics after all - so try and remember not to imbibe while you're getting clean.
I avoid salads and cut fruit as they are most likely to have been washed in tap water. If you're particularly concerned, and/or have a delicate constitution, take a little hand sanitiser around with you, especially if you'll be handling money a lot, or in a crowded place like the markets. It goes without saying that you should of course wash your hands with soap before eating.
I would also avoid swimming in the ocean or rivers (and waterfalls) after heavy rain. Many of the natural swimming holes around Ubud have spring water, or water piped directly from the lake, so it's pretty clean. But a storm will wash rubbish into streams and onto beaches.
Diabetics and sufferers of IBS will need to take particular care. Also if you don't eat a lot of spicy food normally standard Indonesian fare, with its high heat content, will make you more susceptible so make sure to get the sambal on the side. Ask for everything tidak pedas (not spicy).
What to do when you get it
Unfortunately the very best thing you can do is starve out the bug. Don't eat for at least 24 hours, and definitely don't drink alcohol.
The Balinese think the humble coconut is a cure all and actually with its high electrolyte content, coconut water is perfect. Ask for a kelapa muda (young coconut) and your hotel or villa will bring you one with a straw - it's often a good litre of so of vital liquid. I also have a hot water bottle for the first night of cramps - a heat pad will do the trick.
Imodium, and similar, is a broad spectrum drug and tends to just block you up. I have a store of diapet for visitors instead, which is a more natural medicine, and milder than Imodium, but very effective and also super cheap. Some people swear by charcoal tablets which will help if you absolutely must travel somewhere, but Imodium will also do the trick. If you have headaches, fever and aching muscles, take a couple of panadol.
Often its just a matter of sitting (and shitting) it out, resting and not eating anything for a few days. If you're lucky it will be a 24-hour thing. If its been a few days and you are still in agony, go to a clinic - a round of antibiotics will let you continue your trip more comfortably. But if your fever is particularly bad, and the cramps last more than 3-4 days, you might have something more serious which a sample test will discover.
When you start feeling hungry again, congrats! You are over the worst of it. Start off with bananas, plain rice and toast, and keep avoiding alcohol, dairy and spicy food.