Well, if he has a fungal (which I also believe he does), he now has a bacterial, too, because fungal infections don't elevate the white cell count, it's the secondary bacterial ones that usually do it but getting a secondary bacterial infection when there is a fungal infection going on happens almost all the time for all birds and always for babies because of their under-developed immune system.
I would not have done the injections though... I would have done everything orally, but that's me and I am a maniac when it comes to my animals.
I recommend you give the bird some liver tonics mixed in his formula. They will help his liver cope with all the medicines he is taking and will help with his appetite and energy level, too. I recommend non-alcoholic liquid milk thistle and dandelion root extracts.