Suggest Remedy For Skin And Scalp Problem

Hello, is it possible if my immune system is depleted that the one spp. of mite that are part of the natural flora on our skin/scalp uncontrolably multiply and start biting leaving very small, non-raised pin prick red dots on the skin? It's happening to me and the dots are often not in clumps -I just feel a crawling sensation and sometimes a biting sensation and will look down and see a newly formed pin prick red dot (very.very small), but no bug associated with it, it also becomes very itchy. I'm a very clean person and have never had beg bugs or anything of that nature. I do have mild case of seb.derm. on my scalp that is usually irratated by the water in the town here that attend university at and the harsh winter weather. Please help me because this condition is very distracting and its gotten quite bad