Do you ever feel "sick" in your head?

This is difficult for me to explain, but I sometimes just get waves of overwhelmingly "sick" feelings. It's not a feeling of sadness or any emotion that I can think of. It's not depression, either. Additionally, it isn't a physical feeling like vertigo or a headache or anything like that.

The closest thing I can think of is that it's a feeling of sort of being disturbed.

Right now mine is caused by the dream I had last night. I can't exactly remember the dream, but I just have this "sick" feeling about it. I dunno.