First of all I never go to a physician if I can avoid it, loool.
Being in Thailand, I guess I need to to 5 till one understand what I am taking about. The first 4 will tell: Don't dive if you get a problem from diving
Well, your profile doesn't say where you are, or it doesn't show on your posts anyway - and I wouldn't know the local situation anyway, but Divers Alert Network should have referrals you could follow to Ear docs knowledgeable in diving there. We do try to stick to conservative and prudent suggestions here, and for medical needs - that means physicians, preferably those with scuba understanding.
That said, of us divers who avoid doctors unless we can avoid them, two general suggestions...
1-Equalize early, often, well, etc - see the video suggestion;
2-Use the alcohol-vinegar (4-6% often recommended) mix. Some say 50-50; I think Dr.Vikingo suggests 1/3 of each with 1/3 distilled water; I use 1/2-70% alcohol and 1/2 vinegar so it comes out close to that. The US Navy found that 5 minutes in each ear daily worked very well; I just apply briefly after every dive or shower on a dive trip and that seems to work
for me. Before I got into that, I used to get the infections - horrible, painful ones.
We call it "Ear Beer" and use it all the time! Am I wrong or is swimmers ear a cold water problem for the most part? Tropical diving is not such a problem! Infection is common because in most of these areas the locals often raise their stock along the local rivers and the feces often gets washed into the water! Ear Beer after every dive!
I've never heard it being limited to cold water; it may be more common, but I have never heard that. My last infection was after diving the St.Lawrence late in the summer and the water was quite warm; I don't remember the details on the others.
Diving in water high in contaminants may well have their its problems; I am not knowledgeable about such but I'd certainly not want to dive in waters high in E.coli; DAN says that's not what causes Swimmers Ear/Otitis Externa tho...
Despite what most people believe, otitis externa is not caused by bacteria in the water: instead, it's triggered by the bacteria normally found in your external ear canal. Here's how these normally innocuous bacteria can become troublesome.
With frequent immersion, water swells the cells lining the ear canal. Eventually, these cells pull apart - far enough for the bacteria normally found on the surface of your ear canal to get underneath the skin, where they find a nice warm environment and start to multiply.
Next thing you know, your ear canal itches, is sore and becomes inflamed. If left untreated, the swelling can spread to the nearby lymph nodes and cause enough pain that moving your jaw becomes uncomfortable. At this point, the only treatment is antibiotics, and diving is definitely out.
DAN has much more on ear problems, of course - as do these forums.