CEL Misfire on cylinder 5

Hello,

I started getting a CEL code saying random misfire and misfire on cylinder 5!
From the beginning… about 2 months ago I backed up and hit a parking stop and it F*** up my bumper and shoved my exhaust under my car. didn't think it caused any problems so i haven't fixed it yet! One night i misshifted and overreved my engine the next night i had a CEL code saying random misfire on cylinder 1,4,5. I took it to the shop they replaced all spark plugs and coil packs said they couldn't find anything wrong with it! I got the car back drove it around and sure enough same codes! I took it back to them the did a valve adjustment didn't see any bent or burnt valves! but they did say the insides of the cat are shoved toward the front I'm guessing from the parking bumper! i got it back drove it around and a code came back saying misfire on cylinder 5. could this be from the cat and it needs to be replaced? also my dad talked to a guy from the dealership and he said it could have jumped time??? but i think if it would have jumped time if would have bent a valve or something?? I don't know!! any one care to share on this?

Thanks