Trying to figure out what happened in this game is frustrating

I'm old, 54 with slow reflexes and bad aim so I try not to look for fights. Loaded into a LH raid, spawned on road to one of the Chalets (has a tennis court below it). Went into the house and started looting. I'm in the theater. Hear someone come running up grunting and groaning like they were hurt (maybe just out of breath?) Then I hear running right in place like they are running against a wall above me for like 4 minutes. I talk on VOIP, no response. I decide even though I know I'm being baited via an exploit or soundboard or whatnot I'm going to push up. As I exit the door to theatre the noise stops, I hear scavs milling around in the driveway, I exit the bedroom where the noise was coming from push down the outside stair and a PMC steps around the corner and makes an instant flick head shot with 7.62×54. I hate not having kill cams, I can handle losing fights, I'm used to it… but I hate thinking that some scumbag has to cheat and use exploits to beat my sorry ass.