Its probably just a glitch
GLITCH RESOLUTION OPTIONS
1. 2 Many Miscellaneous Quest; check you quest under miscellaneous if you have too many, it will cause the game to get glitchy. Go finish those out and then come back to that quest.
2. Overheating System; If you have been playing non-stop for 4 - 5 hours take a break (Turn the Game Off, Eat, Sleep, Go For a Walk, or Watch a Movie) then go back to gaming.
3. RE-LOAD: Yes, you might lose some experience or have to redo a mission but sometimes it worth it.
4. NEVER, EVER Exploit glitches or use Cheat Codes play the game as it was intended.
I've taken 406 arrows in the knee