I don't have pictures but I can tell you that practically every puppy I've ever had (all the Dobes and the Australian Shepherd) has had docked tails end that looked somewhat different.
Have you asked the breeder? The fact that there is a bump almost sounds like a dock that was done without pushing the skin back so that there was ample skin to cover the tail end--those almost always need fixing as older puppies (often it's done when the ears are cropped and the puppy is under anesthesia anyway.
The the skin isn't pushed back so when the dock is complete it (the skin) covers the tail end without stretching the skin you'll sometimes get something that look like what you've described.
Ooops--just discovered this--I wrote it yesterday and didn't post it--duh!
Good photos. But "Before" and "After" what? Did you have the tail re-docked or was some sort of nonsurgical medical treatment involved? Or did the tail heal simply heal on its own and the hair eventually grow back?
I'm a bit late coming back but thanks for all the replies! I feel more reassured that nothing's wrong with the tail. And in the past week it's healed up better with longer hair at the sides to cover it and he's grown bigger so the scab is looking smaller.
I think he did have a problem with licking the tip and slowing the healing because he's having some issue with his anal sacs and he keeps licking the whole butt area and was chewing the skin around his anus to the point of having little scabs there. Maybe it's some food intolerance but he's always leaking anal sac fluid when he sleeps. I got them expressed but not much came out and it was a normal clearish yellowish colour. Anyway, tail is fine and doesn't need a redock because that turned out not to be the source of the problem.