I am fighting a tail injury as we speak. I had put Lizzy in the bathtub for his daily
bath, and ran in the next room to throw wash in the dryer. When I came back, he was on his back, face down in the water. I grabbed him quickly by the tail and pulled him out of the water by it. A week or 2 later, the tail had what looked like bruises on it. I first thought they were burns from his basking light and treated with neosporin, though there was not an open wound. Below the bruised looking part, I could see the tail turning black and getting puffy. I took him to the vet (St Louis's finest Dr Dan Wentz, I might add) and Dr Wentz told me that he could amputate, but better would be to break the dead part off since their bodies produce something that helps to heal these injuries. He broke the piece of tail off, and had me giving Baytril injections (2 units) every other day for 2 weeks. At the end of 2 weeks, I went back for a check up, and more of the tail stump had rotted, and Dr Dan removed it. He hadvised me to make a Betadine/water solution about the color of weak tea and soak the tail stump for 15 min twice a day. Then, he gave me another antibiotic (cefta?) that I inject every 3 days ( 7 units in each injection). The stump is doing better - that betadine soaking really seems to be doing a lot of good! We go back for another check up in 2 weeks when we finish the cefta. I can see by looking at it, that more of the tail will be removed since that is where the bruise closest to his body was, and like Dr Dan said, that is where the blood supply was broken.
The best way I've found to soak the tail is to put the Betadine solution in a tall narrow pill bottle, and after Lizzy goes to sleep or before he wakes in the morning, I wrap him burrito style in a hand towel with the tail stump sticking out; I hold "the burrito" vertically so that the tail extends down into the bottle. I believe that the Betadine soaking will do your guy a lot of good, especially if you can start it now, before it gets infected, like Lizzy's did.
Dr. Dan is truly the greatest and I feel lucky to have him here to help us. That tail is not going to grow back, and my experience tells me that it will not reattach. Your guy's new nickname is Stumpy, but the good news is that he should make a good recovery.
