Strange white patch of hair on beard

I am in need of help in trying to figure out some symptoms of mine that have started recently. A small patch of my beard has become white/discolored on the right side of my chin, rather suddenly. I also experience twitching in this area. My suspicion is stress or a mineral deficiency, but wonder if this is linked with my history of allergies and dermatitis. Currently I have been getting allergy shots (immunotherapy) for about 2 years and also doing dental work including Invisalign braces at same time. I am scheduled to see a doctor in November but would like to start figuring this out sooner if possible. If anybody might know or have any idea about what these symptoms might indicate, I would appreciate any feedback. Let me know if more detail is necessary. Thank you.