None of my dogs ever had a bad reaction to gabapentin, I haven’t either, but the kittens I was fostering last year got some when they came home from their spay/neuter and one of them was stoned out of her little furry mind for hours. You just never know until you try.
Has she been tried on meloxicam? Old school, but I like it because the dosage can be precise to their weight. But some dogs don’t do well on it.