I was in class today and the girl next to me randomly gets up and high tails it out of the room to vomit. On the way out, she balanced herself on my coat, which I had to then wear. She came back quickly, looks nauseated for maybe 10 minutes, then seems OK to participate in class. Then goes up to lunch, eats a ton of bread and acidic sauce, and hangs around finishing her juice. She looked super pale, but reminded me that she did have a cold too so obviously she wasn't feeling good. Since I knew her pretty well I asked her if she had a stomach bug, and she said probably not since she has acid reflux, 90% sure, but no promises. I pressed her more, and she said usually with acid reflux, a bit comes up and she swallows it, but this time it just came out and she thinks that was it since she only "threw up a bit, not [her] whole breakfast." She also said she wasn't feeling sick at all beforehand or the previous night. I'm still paranoid since I had to sit next to her for another hour while she flung her very long hair around and made gestures with her hands near my face.

Scared, though doing surprisingly well since there's nothing I can do about it now. A bit anxious, but I made myself put on the coat, go upstairs and eat my lunch. I forced it down, but I was very determined to eat! I even refrained from scrubbing my hands down as fast as I could since I hadn't touched anything, I was mostly concerned about it coming off her hands or hair into my face (also I wasn't sure which bathroom she got sick in and didn't want to risk more exposure).

So is it probably just acid reflux? Should I not worry too much about it? Evidence it's not stomach bug:
-Only threw up once, and apparently it wasn't a lot that came up.
-She has acid reflux and this happens from time to time.
-She wasn't feeling icky for more than 10 minutes.
-She didn't spend any time recovering in the bathroom.
-She ate a full lunch as soon as class was over.
-Was already sick with a cough that probably weakened gag reflexes and made her feel yucky (ie prone to barfing).

Evidence she does have a sv:
-She said actually throwing up is very unusual (though I don't really know what unusual is relative to).
-She looked very pale after eating and was walking gingerly (like she didn't want to get sick).
-She did look very nauseous right after throwing up and looked like she was about to at least once more (but didn't).