for three weeks two months ago I had highly disturbing, violent, and gory nightmares. Turns out the cause of the nightmares was extreme anxiety; I fixed this by organizing everything I own, choosing to give less of a forget about certain issues/situations, and focusing on only a couple things at a time instead of everything
but your case is a little different since it's the same violent dream occurring repeatedly-- so it's either a combination of high levels of anxiety and a specific personal issue, or the onset of a psychological disorder. But I'm not a psychiatrist soooo idk