Fwiw I haven't, in years, swam without ear tampons (or is it plugs you call them?) at the risk of pain and inflammation. I looooove swimming, and love swimming under water, but this summer for example, after I had an ear infection I wasn't able to swim under water even with tampons/plugs as my left ear (it's always the left one) would instantly say "No!"
I know that as a child I suffered from rhinitis, and so does my father. I was treated for several years until I was about 18, when most symptoms were gone. Since then I have been having less and less symptoms, the only thing telling me that there is something there being my inability to handle being under water without tampons.
The year where I got the worst ever ear infection was when I swam every day for 2 weeks with a lot of diving. The diving was the real problem, not the swimming, and that put me in bed for at least a week...
Where I'm from, by the coast, it is known that if you swim and dive a lot you can be prone to ear infections, at least that's what I've been hearing since being a child. But then again, it might have been something from the sea in that region.
I can't remember what I've taken in the past for my ears, I haven't had a sea related inflammation for a long time because I prevent it with tampons/plugs (you can also use that as a preventative measure) and am aware of the first signs of ear popping or pain.
Not sure whether this is of much help wetroof, but here's again fwiw. Also, you mentioned that you did a great deal of swimming that was unusual for you, that is likely to have triggered it, but had you also swam in that bay before?