I find that my returning ear infection causes a numb feeling of that side of my face. why?

Trigeminal nerve: The outer surface of the drum is innervated by the trigeminal nerve, the major nerve supply to the entire face so it's possible for an infection affecting the drum could have facial symptoms. I assume by numbness you mean sensation loss and not weakness. If the face weak with infection may have absent bone around facial nerve that runs behind drum. If so then ENT asap.