I don't feel well.

我觉得不舒服。

I fell like vomiting.

我想吐。

Pardon me. I think I'm getting a little airsick. May I have some medicine?

对不起。我想我有点晕机。我可以吃点药吗?

Will you bring me an air sickness bag?

请你给我一个晕机袋好吗?

Do you have any medicine for airsickness?

你们有没有晕机药?

I've got a slight headache, and my stomach feels a little upset. So I want to take a seat near the lavatory.

我头有点痛，肚子也不舒服，所以我想坐靠近厕所的 座位。