Yes, It would stem from the abuse. Rape is about aggression, and control.
Is there a male figure, currently in your life, that has a control issue?...a boss, co-worker, etc?

This could be causing the nightmare. If possible, try to find a counsellor, you can talk to. Your being abused was not your fault, but you are paying the price. If you cannot afford a 'therapist' persay...there are free programs out there for rape counseling.

I hope this gives you some small comfort.
Hugs n' Luck,
J