Apparently the vets administered the vitamin injections without consulting with the owner first!
This would make me go totally ballistic.
Unbelievable.
Please post more pictures of your tortoise in the enclosure and tell us about the conditions of care, like size of enclosure, temperature, lights, humidity level and diet?
You can apply triple antibiotic cream to that spot and watch to see if it starts to heal.
It's adorable and I love your setup except for one thing.
Check the basking log and please be sure it's NOT cedar wood.
The toxins from cedar wood will seep into the water and make it sick or kill it.
Speaking from experience.
I am sorry you lost Trixie, but you are being way, way too hard on yourself.
You were a deeply caring and loving owner, did the best you knew how, and I wish more people who keep animals would put such effort and thought into it as you do!
We love them and we keep learning.
If your tortoise has a nice large enclosure or yard to roam around, you can feed him a big pile of suitable food every day and let him eat as much as he wants. Just remove any leftovers in the evening.
Hi and welcome to you and your tortoise 😄.
Have you tried him with natural weeds and leaves gathered from the wild fields and woods, like dandelions, clover and purslane? Also pumpkin vine leaves and flowers, okra, kale, pak choy?