Awww bless him! I'd think it will diminish over time, the two foster babies I have recently had, absolutely stunk when I first got them, but now they don't smell at all - took about 2 weeks or so I reckon. What are you feeding him? Some people seem to be really sensitive to the smell of burgess excel and can smell bunnies who eat that!
He's looking so much better and happier - big well done to you!