I AGREE !!
Don't know why she's on prednisone ...and after reading your post all I can think of is get her to the VET ASAP - if you don't have one open - find an emergency vet - Panting, trembling and vomiting are NOT good for a dog that age - it sounds like she needs medical attention right away. As far as giving her PEPCID - When my Chanel had a tummy problem - my vet gave her ONLY 1/4
of a 1/4 to settle her stomach - but it was only given under a vets advise.
So - please - don't give your yorkie anything else without checking with a vet first - it could compound the problem ....Seeing the town you live in (under your user name) you should have no problems finding a vet on the weekend & GOOD LUCK to you - I hope she'll be ok !!