skittles,
I think this is a very normal thing almost everyone goes through at one time or another--thoughts flying around in one's head. Sometimes I have to turn the music up real loud to drown out my screaming thoughts.
This can often happen when a person has anxiety. So, No I don't think you are crazy-- just you knowing that it's your mind screaming shows you aren't!
As to your other question--- were you referring to hypochondria?
mandy