She could be stressed out because of the pup, i'm not to sure about cat flu, i guess there could be a chance.

As for the vets saying have her pts, i have been told the same about mine in the past if she was to be sedated cause she is quite aggressive but they managed it with a differant vet so i would take her to see a vet but get a vdifferant vet.

Hope your puddy gets better soon.