Check it early!
Ear infections are not something to mess with. If they make it into your inner ear you could easily suffer permanent hearing loss. It's worth the money to go see an ENT if you have pain along with the plugged up or draining ear. ENTs love to see kayakers with surfers' ear (exostosis) because our ear canals have developed a funky shape an it spices up their day. Even better, spend the money prophylactically and get custom ear plugs that work better than any of the preformed ones. I'll just add one more point: if your body is chronically fighting an ear infection, you're always paddling at less than peak performance.
Vaya Con Rios!