I used a live hair dye cosmic purple,, two days later I noticed a bald patch on the crown of my head,, since then it ha got a lot bigger and I don't know what to do,, doctor said its contact dermititis from the hair dye,, other people have said its like allopecia

I would believe the Physician who looked at the spot and examined you before I would believe non-professionals. What did the Doctor recommend by means of treatment?