What color was the blood and hair on the shaft? Was the fat on the shaft thick, or "greasy"? If it was thick solid fat, I would say you ran your arrow across it's back, greasy, I would say you got guts. White hair would again lead me to believe you got a gut shot, dark hair a shot across the back.

Don't beat yourself up too bad, you just have to make sure you know where that bottom cam is at before letting it rip. Get up nice and early in the morning and start grid searching. You never know, it might turn out okay for you. Good luck!!!!