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It looks like she had an injury or a bite by a sibling towards the end of her tail, that's what has resulted in the "kink" at the end of the tail, which actually doesn't look bad, it will either stay that way for the rest of his life or it will eventually fall off. The open wound that is up further on the tail is the worry, though no, it's not "Tail Rot", as of right now it's just an open area that looks like it was due to a bad shed...just as an FYI, and I'm not saying you did this at all, just in case, don't every try to help him shed by pulling the skin off, if it's not quite ready to go you can end up peeling up the new skin too...
So what you need to do is keep the open area very clean, I'd use an antiseptic like either Betadine or Hibiclens from the drug store or Walmart and clean it out daily, pat it dry, then you can either put a Triple Antibiotic Ointment on it or you can also use a raw, unpasteurized honey (it's a very strong, natural antimicrobial), it has to be raw and unpasteurized/unfiltered, or Makuna Honey, you can apply that just like you would the Triple Antibiotic Cream, then I'd keep it covered with some gauze wrap, and do this at least once a day until new scales form and it closes up.
He may lose that portion of his tail, sometimes they dry up and just fall off, that's okay, but if it starts turning black below where the open area is, then this means an infection has developed. That's what you've got to keep an eye on, hopefully it won't be a problem, but if you see the tissue below the wound towards the end of the tail turn black, and you see the black tissue spreading up towards his body, that's what is typically called "Tail Rot", which is an infection that spreads up the tail towards the body, and if not treated by a Reptile Vet with antibiotics it will eventually spread to his bloodstream. I don't think you'll have that problem as long as you keep that wound cleaned out and put the topical antibiotic cream or the raw honey on it daily. It looks pretty clean and I don't see any dead tissue yet, so that's a good sign.
Just in case you have any "loose substrate" in his tank, like sand, wood chips, bark, rodent bedding, etc., you need to dump it out immediately, disinfect the inside of the tank, and then put down clean paper towels that can be thrown away as they get dirty. Loose substrates harbor and breed bacteria, fungi, etc. so you can't have any of that around his tail....