It keeps regenerating health and runs faster than I do. I'm dual wielding but I can't seem to swing fast enough to get more than two or three hits on it. It keeps running away. This is the first quest I'm doing in Skyrim since I just headed for the nearest city to where I started the game.

lol, i had the same problem. I first thought it was leading me towards somewhere but after following it for about 10 minutes i realised that that wasn't the case.

What i then did was using a bow and get a stealthsneak bonus and afterwards he got stuck into a tree and a rock and with a second arrow he got down.
You could also use somekind of paralyse spel/scroll as well