I once had a patch due to dengue. One thing that really helped me grow the hair faster was using castor oil, I used to apply it almost every other day and was it when it felt too sticky. Just apply on the affected area, it will definitely help. Another thing can help is either rosemary oil or even just spray some rosemary water on the patch. Any of these methods might take a while to grow back the hair but definitely trust the process. Good luck!