The only side effect that I had when taking Seraquel was the severe drowsiness. For the first three days it knocked me on my butt. My husband had to get me up even to eat. after that I slept 18 hours a day. Going into it, I was already in a bad place so my thoughts were bad to begin with, and I can't remember if it worsened or not. I know how hard Intrusive thoughts can be on a person. my best advice is to tell your doctor and see what he/she thinks.
sorry I couldn't help out much