Legionnaire,
I feel your pain. I have lost two deer and it sickened me both times. Mostly because I knew they probably died and did not recover. One was with a bow, the other a rifle. Both had good blood trails to start with, both petered out before finding the deer.
My guess is that one of two things happened. Either the angle was more accute than you realize and you only got one lung (near side, exiting in front of the far shoulder) or so high that the entry/exit holes sealed up and he bled inside only from there on.
Looking back on how it happened for you, I think I would have stopped the tracking job the minute it stopped raining. You'd already gone a good ways by then. Maybe if you had, the deer would have died where you jumped him up. That's what happened to me too.
Don't let it discourage you. I almost stopped hunting because of the last one. In fact, if it hadn't been with a borrowed rifle, the rifle probably would have stayed in the field too! That was a very long ride home.
