An Archer following a running player always has the advantage. Their Heavy Crossbow Moving Shots (or Comp Bow) will out damage your bandages eventually.
When it "looked" like he was 18 away and hitting you, the actual distance when the shot took place was in range. You'll often look like your separation is greater then it actually is. I'll bet that there were times during your jog that he was close enough for a shot, but he didn't shoot? Cause he actually wasn't close enough.
I don't know your char type, or I could suggest some evasion moves for you.