Does your child complain of a bellyache even when it doesn't seem to be true, like they are just making it up?
They probably are. Not because they are "lying" but because parents often respond with care and connection when their child is physically suffering. It just may be the case that your child is feeling NERVOUS or SCARED or GUILTY or WORRIED or SAD and a bellyache is the surest way to get the love they need so much.
Short story? Let the reason for their discomfort be "true", see it for what it really is: a cry for connection. Be thankful they've found an avenue to relief. Eventually, as they trust you to hold all of their feelings sacred, not just the physical ones, they won't need to find an excuse to get connection.
Image credit: Feeleez ABCs