A. If you feel the vet hurt her, find another vet.
B. Gabapentin can be purchased at many places. It probably is what he quoted. You could look online for vet pharmacies and call for pricing. Some of them actually post it online.
C. Cytopoint is fine. I have used it for a very long time without any ill effects on the pups I used it on.
D. If you wish to home cook (allergies to food are only about 10% of all allergies), then you really need to get it from a vet nutritionist. There is a free one at:
www.balanceit.com but you have to purchase the supplements. You do need supplements if you home cook.
E. Try to find the positive and focus on that. Enjoy the time you have with her. Sadly, we never have enough time with our pups.