I don't know anything about glucosomine, mine was given Rimadyl. Is glucosomine an anti-inflamatory? I would give Andy 3 or 4 weeks and have him seen again if he's not doing better. Mine limped with no pain and he had legg-perthes. It takes some time to diagnose that, to see if it gets worse or doesn't improve.
I too can understand your views about some of the replies. Take the good with the bad. Good luck to you and your little guy!