MEDICAL PROFESSIONALS: my younger brother always gets headaches and stomachaches. What’s going on? What do we do?

Our dad has the headache problem as well, but not the stomach problem. My mom won’t take him to a doctor b/c she believes the stomach problem is related to a condition called EDS, which he may or may not have, and there’s nothing he can do. Dairy aggravates the stomachaches, but not eating it doesn’t make them go away. Both the headaches and stomachaches are frequent, but he’s not sick otherwise. We always have to leave outings b/c he has to go home, to use the restroom or just lay down. What’s the solution?