Maintaining a narrow base does NOT improve stablilty. It makes you unblanced, that that is where joint problem begins.
Answer:
an ear infection, consequence of other previous infection
Explanation:
In some cases, when the babies start with respiratory infections, the antibiotic can act in the respiratory system, but if there is some bacteria that can travel to the ears and grow over there, it can reproduce and cause an ear infection, as a consequence of a bad treatment of a bad care of the first infection.