Wow, you sound exactly like a friend. I think he uses Ativan in a pinch with good success but is looking for alternatives--diet, supplements, etc.
GABA works somewhat if he takes tiny doses. If he takes more than that it causes more problems--panic, I think. I don't know if that is a glutamate/MSG type of reaction but I'm fairly certain he does not get much B6. He is new to the natural medicine concept. He does not yet get it that you have to support various pathways.
Magnesium seems to be somewhat helpful too and has been well tolerated--Mg citrate + glycinate + malate combo.
If you try the B6 or multi B and it is helpful to you, could you **please** let me know!? He is in a bad spot and could use a breakthrough.