Nooooooo! Please don't try to play veterinarian! If your beardie has an infection in his tail that is spreading upward towards his body, he will likely need an antibiotic injection from a reptile vet, plus oral antibiotics, plus he may need his tail amputated above the infection to keep it from spreading into his blood stream. There is nothing over the counter or natural that will help this infection. It's called "Sepsis" once it spreads to his bloodstream, and that is a definite dead beardie. So be a responsible pet owner and get him to a vet, or surrender him to a rescue because they will get him to a Certified Herp Vet immediately. It's just what you have to do. Would you rather he belong to someone else that can take proper care of him, or would you rather be selfish, not take him for help, and he die? Because if that infection isn't better yet or has spread at all, he's in serious trouble and needs prescription medications that only a vet can prescribe and administer. As I stated, a friend of mine had EXACTLY the same issue, after a week of putting Neosporin on it three times a day and doing warm water soaks in Betadine the tail was worse and it had moved up the tail, he took him to an exotics vet and he got an antibiotic injection, oral antibiotics for a month, and it still took 2 more months for it to clear up. So obviously "Apple Cider vinegar" isn't going to do a damn thing (just stop, you're way beyond apple cider vinegar or aloe).
It's your call and you're going to do whatever it is you want to do, but I'd much rather give my beardie away to a reptile rescue who would save his life than to ignore what everyone else is telling you because I couldn't afford$100-$200 for a simple vet appointment and medications and just let him suffer and die out of spite. That's the other thing, once that infection starts to spread your beardie will be in a lot of pain if you don't get him to a reptile vet. You need to think about that long and hard.