6 yr old tummy troubles

My 6 yr old has been complaining for several days now of having what sound like digestive/intestinal issues … he has a hard time describing what’s going on, but I think it’s a combination of gas, indigestion, & maybe constipation? He hasn’t been eating anything out of the ordinary, he’s actually been eating less than usual lately. I’ve tried encouraging water & more veggies to get things moving, I’ve also given kids pepto & kids gas relief but it doesn’t really seem to be helping. He was looking pale earlier & I just don’t know what to do. He’s not acting “sick”, just tummy troubles. I’ve been wondering if he might have some type of food intolerance or something going on? But I’m just not sure cause his symptoms aren’t totally clear either.

Advice?