This same thing happened to me a couple years back. I placed what I thought was a nice 30-30 shot into the sweet spot of a beautiful, thick six-pointer. He ran down into a gorge and then up the side of a mountain and over. I took 15-20 minutes to go back to the house and get a dog to help me track. Blood was all over the place and the dog found the scent immediately. We ended up going up and down almost two mountainsides before the trail went into a neighboring farm field and completely stopped and disappeared. Not even the dog seemed to know what the hell happened. I spent all day looking and back tracking to no avail.

Absolutely horrible feeling, but you learn from it and grow into a better hunter. It happens.