I've been having my hair dyed at various salons without any issue for about 30 years. I went in to a salon I've been to many times before yesterday morning for my skin test before my colour being done tomorrow... and it's left me with a badly burnt, scabby, raised and sore mark behind my ear. It did feel quite stingy when it was applied but I thought nothing of it at the time as I've always been fine before. I went back into the salon this morning and they said they'd never actually seen that happen before. Obviously I cancelled my apt and they said to come back in a week to try a skin test of a different type of dye. Has anyone else had this happen out of the blue after always being ok before? What could cause it?