I shot a nice buck Sat night that sounds just like what you have. When I hit him, he jumped, but then he just sort of 'trotted' back to the woods. He went in about 10 yards (30 yards from where he was hit) and stopped and stood there. I watched him from my stand until it was too dark to see, maybe 30 minutes. Unfortunately, all I could see was his hind quarters so I never could get a second shot into him. When my buddy and I finally got out of our stands he bolted into the woods. I found good blood, and white hair. We tried to track him but lost the blood trail at about 60 yards. We decided to back out and try again in the morning. Sure enough, he ran down towards the creekbed and expired at roughly 300 yards from where I shot him.

The strange part was, when I gutted him out NONE of his vital organs or digestive organs had been hit. The slug went in just behind his shoulder and went downward and stopped just under the skin almost at the bottom of his ribcage. When I shot, I failed to compensate for the fact that I was sitting in an extremely high stand, much higher than the 20' stands I am used to shooting from. The slug went in at a fairly substansial downward angle and fortunately did enough shock / cutting damage to cause him to bleed out internally. We thoroughly inspected (ugh!) [:'(] all of the organs and a very small cut on one lobe of his liver, nothing else had been hit.

My suggestion is to wait and give it a good search with some friends in the morning when you can see what you are doing. You might just be able to find some blood in the daylight that you didn't see in the dark. Good luck! We are all pullin' for you!