Had the same problem. I grew to hate Seroquel because although it quelled my invasive thoughts/verbal hallucinations, it sucked away my will to live (even on the lowest dose) because it got so concentrated after days of 50-75mg. I was on 25mg for a couple of weeks before i quit it altogether because I felt miserable, was sleeping all the time, and just didn't feel like doing anything. That was my reaction, but yours may be different.
Wish I had better luck with it...and you too.