Edgy as hell, but why?

[hh339]

I'm quite new to pharmacology, but I know there are some educated persons here that may be able to answer my question and guide me in the right direction. Here it goes...

SWIM has always been extremely tense and edgy, like walking on egg-shells really. Fear would be a good word for it, as would anxeity. He's got nothing in particular to afraid of though, and the feelings are mostly present in the body and not in the mind, if that makes any sense. He's quite shaky. He has used benzodiazepines and alcohol (not at the same time), with very good relief and relaxation as a result.
Now since he is in a different position in life where he can/will no longer use benzos, and doesn't want to drink a lot of alcohol, I wonder what other alternatives there are for him, as well as I am very interested in the pharmacology behind this condition.
The drugs that has helped all affect the GABA receptors in the brain, but which neurotransmittors could be responsible for these unwelcome feelings? Norepinephrine? If so, what can be done to reduce it? Any thoughts would be much appreciated.

Thank you.