Is it normal for my dogs skin to be turning gray under neath her fur in just a few areas? I am worried!?

My dog is a tan sheppard mix, she just turned two. Her skin is usually really pink under all her tan and white fur. but laately when I give her a bath and her hair sticks to her skin and seperates in some areas, I can see GRAY spots! Its scary. nothing is scaly or bloody or infected. it just looks smokey..when her fur drieds u can still kind of see the smokey color underneath which looks just like she got into dust or something, theres a few on her legs and her ears but most of the gray spots are on her back. I am really worried about this and her daddy is not, i tried to too look it up. also shes been really really itchy lately and she has NO bugs. I constantly bath her and i have only found maybe ONE flea on her once in my life. she plays outside a lot but i think she has a skin disease? shes not losing hair and her behaviorism is very normal.