What could cause sharp stomach pain around the belly button area in a five year old boy? and why would orange juice send him into tears?

Meckel's diverticulu: There is a concept called referred pain. Pain felt at the belly button could be generated anywhere in his gut from just outside of his stomach to his mid-transverse colon-in other words, not very specific location. Bring him to his doc and if he is stymied to a peds GI doc. There is also possibility of Meckel's diverticulum. Good luck!