Nearly lost my ability to hear anything due to a barotrauma with a sudden headcold (didn't feel it before the flight, first signs during descent). The valsavala manouver doesn't help in all cases, neither does chewing gum.
Since then on the first sign of a cold i show up at my MD and he will take me off the schedule for at least a week, usually two to be sure everything is ok again. Now, sick days are payed over here and you can't get fired over being sick, employment protection is very high which gives total confidence in rather taking a few more sick days than not enough.