She may have an intestinal blockage from the rawhide. The vomiting makes that a good possibility.
Hydrocephalus can do this too.
But to get back to the rawhides issue - check to see where they are made. Some of them are made outside the US and may contain insecticides causing this sort of reaction in your dogs. I try to buy only US made and inspected treats.
www.petextras.com is where I buy chew stuff for my little dogs.
I've had dogs get quite ill from the stuff made in China or Argentina etc.
I suspect the panting is pain. The Deramaxx may help with that but if the rawhide is blocking her she will need vet help.
The high arched back usually means abdominal pain or spine or hip issues causing pain. It can be an attempt to decrease pain by shifting weight forward on the front from the rear or holding up the intestines.
If she seems generally OK waiting for your vet to open is an option but if she seems to be getting worse you might consider seeing the emergency vet.
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