What health issues do you have? How much apple juice and what kind?
Apple juice can cause mild to heavy gas in some people. I've found I can't drink near as much freshed pressed juice (the yummy thick stuff) as clear juice, probably because of the increased pectin. If I drink more than one glass of pressed, I get really horrible gas. It takes almost a gallon of clear juice before it starts to affect me.
Another thought might be the malic acid in the apple juice has softened some 'stones' enough that they've moved forward some.
Either way, if you don't have any health issues that the Sugar in the juice may be aggravating, the flush should relieve the symptoms you describe.
I'm doing... I lost count, flush 10(12?) tonight so welcome aboard!