There is often a lot of confusion among divers about ears, water in ears, and ear infections. To help clear this up, I wrote a little
article about the difference between outer and middle ear problems in divers. In addition, Dr. Kay's
video on the diver's ear is a superb resource.
Barotrauma of the middle ear looks, on exam, very much like an ear infection. Since ear infections are what primary care physicians are used to seeing, they are very likely to treat barotrauma with antibiotics, even when no infection is present. The lack of improvement with treatment is not a sign that the infection is resistant, but rather, that it wasn't infection in the first place. Nothing you put into the external ear canal is going to affect a middle ear condition of any kind (unless the eardrum is perforated).
The sensation of fullness and muffled hearing, with crackling or popping sounds, which is persistent for more than a few hours after diving, is almost always middle ear barotrauma, with fluid accumulation there. It takes days to weeks to resolve. This is a very common problem for new divers, who get distracted by the demands of buoyancy management and forget to clear their ears as often as they should.