Thanks, I try to use what I've learned from CBT to rationalize my sensations and symptoms - its just that some times the brain gremlins win.

I've spoken with my GP since my original post and they believe that what I'm experiencing is being caused by excess adrenaline from stress and anxiety - it will be some weeks yet before fluoxetine is in full effect so I'm just doing my best to stay cool and not panic when I get these sensations.