Most dreams are stress/anxiety dreams; we don't "need" pleasant dreams for anything. If you can, I would work with your dreams during the day, "acknowledge" the flesh eating monsters and figure out what that could represent to you, what you are afraid of and try to remedy the actual, daytime problem? The particular nightmares can't go away until you consciously acknowledge them and their "help" in keeping you balanced as best they can, giving you the bulk of your fears at night instead of when you are trying to make it through the day.

Personally, I think I'd try to find a friend willing to sit through a zombie/flesh-eating disease sort of movie with me and watch and discuss it with them as it is going on, etc. I'd maybe think about a previous night's dream and "name" the creatures, as if you are familiar/friends with them; they are your creation after all, you've made them as a sort of defense for yourself. Side "with" them and you won't need them as much, your unconscious will know you have gotten the message and are working on whatever it is that is causing you so much stress/anxiety during the day.