I now have a few areas of white scalp which I can see coming from where the hair fell out. Will it grow back?
Dyes can be dangerous when they are improperly used and you most likely had a chemical burn from inappropriately used dyes which goes deep below the skin to kill the hair follicles in many instances. This is unfortunately common and these chemical burns most often cause permanent hair loss. Hair transplantation works if the burn is not too extensive. ?Scalp Micropigmentation also works in some situations (see here: https://scalpmicropigmentation.com/smp-for-women/