Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 15 years of experience. I look forward to working with you.
Sounds like you're working hard to clear this up for Heavenly. However, mange is very uncommon in cats. So, I have a few questions to try to help me provide you withe the best answer possible.
1) Was this diagnosed via skin scraping by your veterinarian, and if so do you know if this is sarcoptic mange or demodectic mange or another more atypical variety?
2) If this was no diagnosed by your vet, and based on the face mange is highly uncommon in cats, then could you please provide a picture of what you are contending with (attach via paperclip icon)?
3) Does he have more than one lesion and if only one where is it located, and what does it look like (scaly, scabbed, red/raised, itchy or not itchy, etc)?
Thanks for answering a few further questions.
And, to briefly answer your question about a shot, there is no mange we treat with an injection any more, although there is one type that could potentially be treated this way. Again, mange is very uncommon. In fact in all my years I have only seen it once and it was not the type that responds to an injection. So, instead we more typically see ringworm, bacterial infection or immune-mediated diseases (eosinophilic granuloma lesions, immune mediated diseases) or allergies that cause skin problems.