Stomach and gut issues - any advice?

So, I’ve got these sudden gas issues (😲), and honestly, they just came out of nowhere.
It feels like there are literal worms wiggling in my stomach non-stop.
I can actually eat fine and I don't have a fever or anything, so everything seems okay on the surface, but my gut is definitely acting up and things are just getting worse. I feel a little nauseous, though I haven't actually thrown up yet.

I haven't taken any meds, and I'm being super careful—eating plenty of fruit, sticking to water and herbal tea, and keeping my diet pretty clean.

Is there some kind of bug going around right now or what?

Three things are currently running through my head:
1) I baked some cookies yesterday using baking powder that expired about two years ago.
2) I went to the sauna recently... could I have picked something up there?
3) I was sleeping with my boyfriend the other night, and since then, I haven't been able to pee properly. But what does that even have to do with my gut?

It could just be a mild stomach bug or maybe some food poisoning. If this keeps up for more than a few days or if you start feeling significantly worse, you should definitely check in with a doctor. It really shouldn't be a major issue.