You know those TV ads for yoghurt that contains "good bacteria"?
Well, you already have lots of good bacteria living inside your intestines. Some were given to you by your mother when she breastfed you and some you’ve picked up during your life from the food you’ve eaten.
They all live happily inside you, helping to digest the food you eat.
If something throws them out of kilter- say some new bacteria try to muscle in on their territory (food poisoning), then you become unwell; your small intestine becomes a battleground, food is not digested and it exits anyway it can- vomit if it’s near enough to the top, or diarrhoea if it’s lower down. Your bodies own defences get involved to sort out the problem (this can also result in D&V- your defences don’t discriminate between "good" and "bad" bacteria- both are alien to the body. The helpful ones are only tolerated in the digestive system because technically it’s outside the body (not in contact with blood)).

I digress.

Basically, you’ve had a bacterial infection & it’s getting better.

Don’t worry about having lost all your good bacteria- colonies hang around in out-of-the-way places like the appendix and will pop out and start repopulating your gut as soon as the cost is clear.
Interestingly- when you go on holiday and don’t drink the local water ‘cos it’ll make you ill; the reason the locals get away with drinking it is ‘co they’ve been drinking it all their life and are already colonised with the local bacteria. They’d probably have just the same problem if they started drinking your local water.
Bottled water has all bacteria removed from it to make it drinkable to everyone.

It sounds to me to be bacterial, but only tests can tell and you may be past the infectious stage, try places where hygiene is a high priority in future, when you choose to eat…..