Muz,
You have a good chance of finding him......Get back to the last blood and start there. DON'T let your legs get in front of your eyes and mind. Piece it together and take the trail to the deer.....don't invent one on assumptions.
The sign will be there, go a drop at a time on your hands and knees.....you'll find it, and I have a feeling it might surprise you where it goes. Don't make blind assumptions until you've worn your pants to the bare knees......it only takes a few drops to point you in an entirely different direction than you expected.
DOn't just assume downhill and water......keep all options open.

ANd again above all else don't rush ahead HOPING to find him.....track him. That animal has 360 degrees of options to work with.
Good luck and keep us posted.