Luxating Patella Problem, Can't even walk

My dog was outside 2 days ago when she started screaming in pain. When we brought her in, she would walk a little bit than scream in pain again and lift up her leg. I took her to the emergency vet (since this was at night) and they diagnosed her with obeseity and 2 luxating patellas (knee caps out of place). She is a 12 pound min pin, and she should only be weighing 7.5.

They said I need to see the Orthopedic Specialist and look into surgery. Well, I also found out my gf fed her some grapes which I didn't know could be toxic. The nurse knew this but just advised not to feed her these, but all other conditions seemed fine during the check up that they did not seem concerned with it.

Well it's Friday now and no orthopedic surgeons can see my dog until Monday, meanwhile my dog has completely lost appetite, hasn't been drinking (i haven't seen her) and has not peed or pooped since Wed. She also can't walk more than a few seconds before screaming in pain and hiding under our bed. She's almost immobile right now completely and doesn't drink. We have pain meds we been giving her too.

What should I do until Monday to get her to eat and poop? Only way I can get her to sniff food is if I put a tamale in front of her (obviously I"m not feeding it to her, just testing her appetite) but regular dog food doesn't interest her and she usually tears it up all up.

quick update: she is eating, she just ate a small bowl of dog food...still have not seen her poop or pee. I keep a water bowl in front of her, not sure if she's drank or not.

does anyone have suggestions? I think her knees are just so bad she can't move, but I can wait until Monday for that. What I'm concerned with now is that she's not using the bathroom and I'm afraid it's because it hurts her too much to walk. Usually she has to walk and sniff around before she squats and pees/poops. I don't think she should go the next 3 days without using the potty. She is eating tiny bits and drinking barely.

If you think she's in pain, I'd be calling the vet about it. They may be able to give you a different med or offer better suggestions since they have seen the dog.