Lisalan gives good advice, also, read suboxone/subutex FAQs at bottom right of this forum, I found it helpful.
I never heard of being weaned off with Flexerall and whatever. How long did he wean him off for? Everyone i know just cuts down on the suboxone. My roommate was on it for a long time too and her and someone else i know that weaned off went down in halfs or quarters. They stayed at a quarter for a while. My roommate was taking a quarter every four or five days because she would start feeling lousy if she didn't, then finally went off. Talk to your doctor. If he wasn't weaned off for a long time, he will probably feel lousy for a long time unless he talks the doctor into giving him a small dose to stay on for a while, then try taking every other day, then every three days, etc.
What dose did he stop at? From what dose did he taper and how fast? How is his health otherwise and does he have a fast metabolism? Many things play a role in the withdrawal.