OK, first thing I would do is contact your primary care doc in the morning, tell them you were in the ER with diarrhea and had some tests run, and that you need to have stool cultures done.
I wouldn't take the antibiotic, at least not yet. You don't know what you're dealing with. ERs often do that - sending somebody home with an antibiotic - before they know what the person even has. If it's an infection you have, an antibiotic might well be needed. But you don't know yet whether you have an infection, nor what kind of infection it might be, so you don't know which antibiotic would be needed.
And if it turns out that it's not an infection but is something like ulcerative colitis (or Crohn's disease), the antibiotic might just make it worse.
So get the stool tests done as quickly as you can, and go from there with following up with a GI for a colonoscopy.
Frankly, this doesn't look or sound like UC to me. And it's very unlikely to be cancer, especially at your age. It's most likely either an infection (a bacterial infection due to what is commonly called 'food poisoning'), or it *might* be Crohn's disease.
For the time being, you might want to eat a bland diet (rice, chicken without skin, plain potatoes, yogurt, bananas, etc), and avoid nuts, seeds, raw vegetables, things like that, until you know what you're dealing with. And make sure to drink fluids to stay hydrated when you have active diarrhea.
Yea they didn’t order anything stool test but I have a stool test kit at home that I haven’t used. What’s Crohn's disease? Idk anything about
any of this. Is it worse then the other?