Let me get this right, an EXTERNAL examination showed fluid in your ear canal, not the eustacian tubes or anything like that, and no wax build up whatsoever?
Old folk ( not old folks, i mean, folk remedy, since hydrogen peroxide was discovered at least) remedy of hydrogen peroxide, suitably diluted, for removal of impacted ear wax-( the bubbling stuff nurses put in your ear if you have impacted ear wax) it also work against infections, just DYYDD, and dont burn out your tympanic membrane with incorrectly diluted stuff.
If you had barotrauma from flying, you would know all about it- so unlikely.
A situation like this can also occur from being to wet behind the ears, though, i have only anecdotal evidence in that regard.:smart: