Why do i keep dreaming about ZOMBIES chasing and attacking me?

Hi im a 20 yr old female and almost every night i have the same dream, im driving with Chris (my fianc�e) and i look up into the hills ans see a field and farmyard sort of areas and i say that i want to go and see it, so we turn around and when we get there its chaos, there are zombies everywhere, we have to barracade ourselves in a room with everything up against the door, all i could keep thinking was that we have no food, bedding etc, then we escape and cross a stram (we're in a landrover now?!?!?) and we get stuck im high up on a ledge shooting the zombies and suddenly all my family are there helping me, but three of my lil sisters are killed, its devestating and we escape to a derelict hotel and lock ourselves in again, and it keeps going on and on and on and i end up going to see if everyone is okay at work (as if i give a sh*t lol) and there all high up on containers and units shooting them.....does anyone know what it means? or what its telling me? its so scary and terryfying. everyone keeps saying its because i've recently played Red Dead Redemption Undead nightmare but the dreams we're happening before that aswell for a long time, dont think the game helped but what does it mean and how can i make it stop :/