.. well, today, when I went for my apple juice, I had again unpleasant pain in my stomach (not that pleasant at all)... So I have two extra guesses why it could have happened..
1) not organic juice... I also bought those apples with reduced rate so I guess the reduced freshness also took its toll.
2) People could also experience that unpleasant feeling after drinking apple juice IF the stomach was not emptied from the Previous meal........ and I said it again, beside all that it could happen due to not that strong stomach.