That could be something called "Tail Rot." I thought it was just something that can happen when the skin on the tail isn't shed and tail begins to sort of rot... It doesn't look like a shed thing, so I checked all my lizzard care books. One of them, "The Bearded Dragon Manual" by Philippe de Vosjoli, Robert Mailloux, Susan Donoghue, V.M.D., Roger Klingenberg, D.V.M., and Jerry cole, said that Tail rot is when "the tail tips have darkened, which eventually spread and part of the tail was lost." It says the popular term for that situation is "tail rot." It says it's caused by 2 things. "The first is trauma, such as an injury from nipping, or from being crushed or compressed by landscape materials. The other is accumulating tail tip sheds."
The book doesn't show a picture, but I would imaging that that It would look worse that the pictures that you put up. If you think that this could be what your little guy has, the book says, "The first step should be to dip the damaged tail in a hydrogen peroxide solution as soon as it is noticed. This softens adhering shed skin, allows for it's removal, and helps nip infection in the bud, so to speak. Dipping the tail in Betadine also works against infection and prevents the spread of tail rot. If this doesn't work, consider seeing a qualified reptile veterinarian. The best weapon against tail rot is prevention: keep babies segregated and well fed, making sure there are no landscape structures that can cause trauma to the tail, and soak bearded dragons in shallow water dishes to soften adhering skin."
Like I said, the pictures don't look that bad, and I have never personally had a bearded dragon with this, but If it seems bad up close, this could be what it is. I don't think peroxide can do any harm if you wanted to try it, but if your worried about it, a vet always knows best.
