Budgie Feet Turning Black

hi good day all i am having an issue with a male baby budgie i bought from am pet store ... he was in good health but suddenly his left foot started turning purplish black and now its bleeding i have carried him to vet and ave gotten anti biotics and pain killers but im now seeing the dark colour spreading upwards onto his body i am cleaning the area with a mild epsom salt and water mix wanted to know if you guys who has more experience than me can offer any advice ..... its my first time keeping budgies and im a bit worried about him , i have removed him from the main cage and put him seperately incase its an infection that can possible spread ...

Edited October 22, 20204 yr by adesh chubs
forgot to include pictures