Dog's can have suprisingly sensitive stomachs - and yet if given the opportunity they will eat cat/dog crap and drink from the toilet.
Beware of the vet. Many I've come across are out to get you financially. They play your emotions "You only want the best for Fido right" and then guilt you with useless and/or unnecessary proceedures/drugs. That said it sounds like your dog needed some attention (hope she's doing better) but you were right to make a break for it. We always give table scraps to our German Shepherd, Ryker, but very small portions of something good (fish, meat, egg) mixed with a little rice and his normal dry dog food. His absolute fav is salmon.
Ryker got into a "disagreement" with a older male wiener dog about 1 year ago. Since Ryker was the aggressor (and it was all my fault - off leash chasing tennis balls) I was at the vet with my Visa card out. Needless to say the vet realized my vunerable position and took it to me ordering every test that could be done, probably a psyc and AIDs test as well (on the victim dog) causing the bill quickly swell well North of $1K.