My Mother Is 81. Her Left Low Quad Of Her

My mother is 81. Her left low quad of her back (roughly five inches squared) with partial radiating line of two inches to lateral line only, is a painful patch of red with no raised bumps. She's kyphotic so the upper portion of her back doesn't truly rest on the chair. To me, it looks like she is developing a large type bed sore from sitting in her chair. She watches tv. She knits about two hats a day for the homeless in the area. I plan on getting an appt for her but the wait is about two weeks. I would like advice on treating it in the mean time. I have seen this skin condition during my six years of convalescent care. Thank you for your help.