It is most likely irritable bowel syndrome from what you describe, which is nothing to worry about and is very common but I would see your doctor just to make sure. They might want to run some checks to rule out anything nasty. There are some foods/drink that set me off sometimes, like some fruit juices. Like you said, it is prbably an ingrediant in those ciders that sets you off. Compare cans or bottles of ciders that give you problems and those that don't and see if there is anything in there that could be the problem.