Currently the feedback when pushing zombies away is kinda weird. It actually feels like when you attacked the zombie but theres no red flash effect on the entities nor any damage dealt.

A sound effect like https://pixabay.com/sound-effects/people-colliding-43479/ should be enough to do the trick.

Also about the camera flickering, I personally thought my game was broken when i first saw that bc it feels kinda like a glitch. A humble suggestion is replacing it with a drastic FOV drop, like you got 0.5 second of slowness. no need to be too much, just so players can tell that something happened, together with a sound effect, that's perfection to me.