What did the arrow smell like? It looks like good blood on it and I don't see any gut matter on it. You said he stopped and walked off slowly, it sounds like he was hurting pretty bad so probably a liver hit. He is most likely bleeding internally is why there's not much blood. Your best bet of finding him is to go walk the woods in a semi circular pattern widening the pattern with each pass. If he's liver hit he'll lay down probably within a 400 yard radius if he isn't pushed. With the rain and not being able to use a dog it's going to be a body search. Good luck with finding him.
