Hey, I was on Seroquel and my dreams (and nightmares) were as vivid as when I was high-altitude camping. Seroquel WILL make the dreams more vivid and you'll remember them, but "what" you dream is something else. There is dream analysis and some common dream themes that you can look into (I'm not sure about any of it), but my take on the "not being able to scream" thing is that your dream is a very common anxiety dream. There's also the "not being able to run away" or the "you punch somebody, but find that you have no muscle strength." There's the MEMORY dream, (like one that I have) but that is one that plays over and over and NEVER strays from the details.
;)
The dream is different than the drug. The interpretation is going to be different for everybody, but in my experience, it's how you choose to DESCRIBE the dream that's important. The important thing for you is that you weren't able to scream and, since you're on this forum in the first place, ... something happened that you think will happen again? I don't know.