I've seen several posts about this similar to mine but not exactly, so I figured I'd ask myself.

Every so often, it ranges from maybe once a week to once a day, I get very intense feelings of deja vu, I guess you would describe it. However, usually how it starts is that something happens, I get a feeling of deja vu from it, and then an entire scene plays in my head that is completely separate from what is actually going on. It's not as if I hear people talking or see them, I kind of just have a strange notion of something going on. It's hard to describe.

It's never unpleasant, in fact I used to try and pull myself out of it however usually when I do so, I'm filled with a very pleasant and happy feeling and try to stay in it for longer to see where it's going.

Afterwards, I get terrible headaches and sometimes nauseous, as well as just a general feeling of being "out of it."

When they happen when I'm around someone I'm comfortable with, I usually just sit down for a minute. When they happen in class where I can't really tell anyone, I need to get up and walk around a bit.

I do consider myself someone who has slight anxiety problems but this actually doesn't really worry me much. It only worries me that it'll happen when I'm driving or something. I don't dread these occurrences. The only times it really bothers me is when I'm getting them several times a day, but I don't mind the occasional flashback.

This has been happening with varying frequency for about a year and a half.

However I'm just concerned that there might be something wrong with my brain or something because it is definitely a feeling more intense than an average deja vu.