One of my pupils is suddenly bigger than the other, but I feel fine. Am I supposed to do anything about it?

I'm seventeen, female, and I live in the US. I don't really have any health issues, and the only medications I take are antihistamines and the pill.

I woke up this morning and when I went to brush my teeth and looked in the mirror, I noticed that one of my pupils was a lot larger than the other one. I thought that maybe it was the light change from waking up or something, so I ignored it and thought it would go away.

But it's the evening now and it still looks like that. I looked it up online, which I know you're not really supposed to do with health stuff, but it made it sound like it's a big deal.

All the serious causes they list seem to be a bit more for older people, and I don't feel that bad at all, I feel fine, so I guess I'm just a bit confused about whether it's a big deal or not. Sorry if this is a stupid question, I've never had this happen to me before.