Bad Rash on my dog's tummy?

I am calling a vet for an appointment first thing this morning but I can't get her in until probably Monday due to work. My shih tsu has this horrible looking rash right around her genital area and in small spots on her thighs. I first noticed it a couple of days ago after ruling out the reasons for her scooting on the floor as worms or her anal glands. She's itching it and licking it consistently to the point where she's starting to rub it raw. She won't even go for a walk it's bothering her so bad. She's 5 1/2 years old, and hasn't had any allergy problems in the past. I tried some children's benedryl just in case, didn't seem to help. I've also tried and antibacterial cream I have to see if that would help. I'm trying to keep the area clean with soft soaps. Does anyone have any recommendations of things I can do to help her until I can get her in to the vet? I feel so bad for her right now.