I would also look for a deer walking with it's toes spread apart. That is a sign of a wounded deer trying to keep it's balance. But as others suggested go to the spot you last saw him and tie a ribbon on a bush or tree branch ect.. Start making small circles and expand them out as you keep searching. If the deer is hit where you say it was it would be dead by now that is for sure. I shot one that ran roughly 300 yards on a double lung shot a couple of years ago. It was light rain that day and all the blood got washed away while I waited before searching. That one fell while trying to circle me but it took a couple of hours to find it.. I would also be trying to here crows fighting over it by now..