Mybe twice a month the put a bet on of my collar will break out, why?

It seems to other happen at most minuscule twice a month. It lasts for one or two days and next goes away. The results are pimple-like bumps. At first, I thought it may be from the roast. It also happens contained by the winter months. I even had my barber stop shaving in that during my hair cuts. Now, after several years, in that is scarring there.Mybe twice a month the put a bet on of my collar will break out, why?
It could be your detergent, anything you use to wash clothes, try ALL Free and Clear....or Dreft.
My brother get the same item. He also gets it on his cheeks, and around the tops of his arms. It seem to happen to him at the vary of seasons or within major warmth changes. The individual thing that seem to help him be going to a dermatologist where he be prescribed a cream and it seemed to shift away pretty fast. Hope this help.