Zara,
I began giving my son IP6 when he was 8 or 9 years old. He didn't have any stomach associated problems with it. If your child is not tolerating it well then you can stop it. As with anything you should start at a minimal dose with anything, including IP6. I would give him a break and at a later time reintroduce it in very small quantity and slowly over several weeks give your child the full dose.