Never took Vitamin B12, This happened to me out of nowhere. When it first started my husband used to tell me to wear long sleeves cuae if we were shopping for clothes salesperson may be r reluctant -- never happened. It just continually got worse. Went to local Dermatologists and none could help. Also went to Allergists and had manty tests. Nothing.
SPomeone recommended a well kn own Dermatologist in NYC. We wen t to him for many years and was prescribed all kinds of topicals and pills and shots. NOthing. took him afew years to say it was BRP. Meanwhile I came up with my own remedy to treat thje BRP, It works better than anything ever prescribed. BUt I still continually have breakouts. No cure for this. I hope you do not have this -cause it will mean a long time of discomfort.