Ram, don't give up just yet. You mentioned he was quartering away at 20 yards, how sharp was the angle? if he was quartering away at a sharp angle there is a good chance the arrow drove up into around the stomach/liver area maybe further. I once shot a doe that was facing almost straight away from me, the arrow entered about 1/2in outside the hip and exited in the middle of the chest, she only went about 30 yards and dropped. Its hard to tell from your description, but i wouldn't give up just yet, he might no be very far.