thanks for your query at HCM
gripe water is not recommended for colic
, stop using it.
if child has colic give colic aid drops 8 drops before feeding that will help .
children can pass smelly stools its common, if its really foul smelling and you cana see pus then you need doctor consultation.
there is no age limit for flight travel, but avoid travel till child is atleast 6 months and also immunity will improve by that time