Could be wrong but I was doing some research into my sons migraines and some children can get Abdominal migraines. I can't remember what it was all about though.. Maybe have a google and see if the symtoms fit??

Quote from a site I just googled

An abdominal migraine is a variant of migraine headaches. It usually occurs in children who have a family history of migraines. Abdominal migraines are rare in adults, but about 2% of all children may get abdominal migraines. Females are more affected than males.

Children that experience abdominal migraines typically develop migraine headaches when they get older.

Although abdominal migraines are in the migraine family, the pain occurs in the belly. Usually, it’s near the navel or midline. Abdominal migraines frequently occur as a reaction to a migraine trigger. They can cause severe stomach pain, nausea, abdominal cramping, and often vomiting.