I understand the idiomatic nature of "dor de cabeza" and "dor de estômago", but is "dor do estômago" so unusual as to be considered wrong? (DL rejected the latter.)
sorry, I didnt mean the word "barriga", but the verb "ter". We usually use "estar com dor de..." and not "ter dor de...". So, you here "estou com dor de barriga" as well as "estou com dor de estômago".