So sorry to hear that you have joined the ever growing club! However, we are all here to support and help each other and I for one have found it invaluable. Like you without reading everyone's story I would have continued putting Minnie's "funny" behaviours down to her just being Minnie. Once Misty is settled on her medication you should find an immense difference in her.
As to getting the Gabapentin - I found Tesco's was the best with a prescription from my vet.
Minnie-May (6yrs) & Rosie the Rescue (approx 6 yrs)
My Darling Cinders and Lady Jane waiting at the Bridge