weird bad dream, I'm not feeling well now

I had a dream yesterday where me and 3 guys were trying to shot a man down , I don't really remember why. he was shoting back but no one got hurt.
then when he got careless I grabbed the gun out of his hand , pushed him away and told the other guys "hey its ok now".


they grabbed him and started to eat the skin out of his head. like taking it off with knifes or something .
when I looked at the guy.....his head was bleeding a lot and he had almost no hair at all. he was still alive.

then I woke up not feeling good at all.

this dream really got into me, my mood today was really really bad , I'm feeling terrible.

can you help me understand what is it ?