I have the same problem and have had a lot of trouble with swimmer's ear. I wear ear plugs when I swim. I've found that silicon ear plugs work best. I do what they tell you not to do - insert it in the ear canal a bit and only use about 3/4 of one. If water gets in my ear anyway jumping up and down until it comes out is the best way to get it out. I use a mixture of 50% vinegar and 50% rubbing alcohol applied with a q-tip to dry out my ears after showers and swimming.

I've used the wax ear plugs and they work well for me.  I use them especially in colder water since cold water in my inner ear adversely affects my balance when coming out of water. 

I usually get water in my ear when training without the wax ear plugs.  After swimming I merely pour a tiny amount of alcohol into my ear with head turned up sideways allowing alcohol to run into my ear.  Then reverse the head allowing alcohol to run out--which it does freely taking any water with it.  No sting at all.  Also, good way to kill any fungus or bacteria lurking in some lake waters.