I hate to sound like I'm always defending the vets but you wouldn't want her to take off more than was necessary. After all the tail does help with balance. I don't believe that it is her fault that a pot squished your lizards tail and she tried her best with surgery and now it's not healing as well as you or her would like. Reptiles can take an exceptionally long time to heal. They are much slower than mammals. It is a good idea to get your buddy looked at again and it may be necessary to do an additional surgery. I doubt an antibiotic injection at the site would really do much if the blood flow is decreased which I would highly suspect but that is her call to make. The face definitely seems as though it may be mouth rot. I really hope that you and your veterinarian can work together to make Calais feel better. Good luck with treatments it's not fun but it's the best chance you guys have.