scared the crap out of me and my husband

..... And now I can't fall back to sleep. So I have no idea what it was I was dreaming but I know it wasn't good, I can't remember details but I just have that feeling that it was something awful and scary, which isn't normal. Anyways so I obviously have a nightmare, my husband fell asleep watching the purge and I just woke us both up screaming uncontrollably because our cat knocked over a giant box of things that was on a table in the room and I feel like it somehow coincided with my nightmare. Needles to say my husband woke up in a panic freaking out and grabbing on to me and it took a few seconds for me to calm down but now I'm still trembling and wide awake! Why????