red,irrated skin on my 18 yr. old cat

Hi, My sweet, old , cat has a very red inflamed under side. There are bumpy spots that look as though she has scratched and irrritated. Recently I purchased a new fabric covered bed for her. Could she be allergic to the fabric ? She has not experienced this before and I'm concerened for her health based on her age. I will take her to our vet tomorrow but would love to hear from you as soon as possible. Thank you.

Mary