Why Does One Get Too Many Thoughts?

I am 23 female and a management consultant. I have been a very quick learner and a achiever all along and even at work I have been very quick. Sometimes I get too many thoughts in my head at the same time and it feels like my head is exploding - I think like crazy and I feel my brain is just running !! Its like zap zap zap !! I get really scared during these times wondering if its a bad thing or a good thing that I think fast !!