I wear a c-pape machine and sometimes i get a sore on one or both sides of my mouth and my mask just covers my nose and my nose and my nose get dry like a plastic coating around my nostrils.what can i buy to help heal the sores and make my nose stop hurti

This : This is a common problem i see with patients who use a c-pap. The proper treatment depends a bit on the exact location and clinical observation so i would recommend you consult a dermatologist. Sometimes i recommend Hydrocortisone cream with a thin layer of zinc oxide paste over that to help reduce inflammation and irritation. Other cases, just a little bit of vaseline. I hope that helps.