Good luck Ram96, Sound like to me disorientation is seting in and he will go lay down. If you get this before you go, be careful, glass for him alot if possible. In this mode he could get up and make a death run and leave very little sign. In your favor, wet ground should leave better hooves sign. I shot an elk a couple of years ago on a step hill, right through the lungs and into the shoulder bone on the far side. No low hole, no blood trail, all the blood stayed inside. The hardest track job I ever did, it was all foot sign, bent grass, snaped twigs and stuff like that. You may be to that point, go slow and look for everything and keep thinking. The buck should go for water and cover, I know you already know these things, but the brain does weird things when you have a unrecovered animal out there. So stay cool and keep after him. If the unthinkable happens and you don't find him, YOU HAVE MADE A GOOD EFFORT, don't beat your self.
Gselkhunter