It sounds like Jera does hyperesthesia syndrome. That twitching of the back and then suddenly licking and then running around is very classic for that. It may be that stress plays a big part in the manifestation, however. We don't know a lot about this syndrome, so I think every cat can present a little differently.
Here a couple good websites you might find useful: http://www.VeterinaryPartner.com/Content.plx?P=A&A=1998 , http://www.VeterinaryPartner.com/Content.plx?P=A&A=3000 , http://www.VeterinaryPartner.com/Content.plx?P=A&A=2873
I think the Feliway is a good start. I find it to be very helpful in calming cats. I also have a cat on the gabapentin and he is doing very well.
I would definitely talk to your vet about oral medication if the Feliway and food don't seem to help. Has your vet done any bloodwork to look for underlying diseases that might be contributing? I would definitely do that before starting any medication.