Time for cat euthanasia

We are near Yuma for the winter and kitty took a big turn for the worse. We found out she had cancer ( not sure where) last June. She was eating good and acting normal til last weekend. She hadn’t eaten, drank, or used the cat box since Saturday or Sunday. Today I’m calling around to have her put down and can’t get in. She doesn’t have a regular vet down here and they all want to do a full exam and can’t get her in from a few days out and one vet was a month. Guess I’m stuck just watching her slowly die on her own. Even the humane society said one week!!