Hi J.,
I have more than 75% hearing loss in one ear due to repeated ear infections. They were not always so painful that I mentioned it to my mother.
He certainly can have a bit of fluid in his ears that isn't draining. This can be cold related, allergy related (his tubes may be a bit swollen due to his recent illness and the fact that there are a lot of irritants in the air right now...) or simply from a bath/shower.
One thing I've learned thru personal experience, is that before a shower or swimming, don't put your fingers in your ears, or q-tips, or whatever. It seems to disrupt the blocking effect that occurs in your ears and keeps water out... like it pushes the hairs into the coating of ear wax that surrounds the entrance (even though you can't really see this wax, it's still there in a fine coating) and allows water to just pour in. Once it's in, it's hard to get out if your tubes are swollen. I have had to use 'swimmers ear' drops from time to time. But really your best bet is to bring him to the doc, and have them look in his ears to make sure there is no inflammation (ear infections aren't always painful). Ask if you can use swimmers ear, or even benedryl to help dry him up if they suspect fluid is in there.
Good luck... I hope all goes well :)