I had a few Swimmer's Ear bouts after dive trips early in my diving. That last one had me in some doctor's office on a Saturday on the verge of tears. Since then, I mix white vinegar and 50% alcohol, stick a dropper bottle in each mask box & my toilet kit, and use it after every dive and every shower on a dive trip. It's worked well for 15 years or so, and it's virtually free. The US Navy has divers add it to an ear, lay on the opposite side for 3 minutes, then turn and repeat - but I'm not that disciplined. I just use it as a rinse every time my ears get wet - fresh water, salt water, shower, whatever.
I also have opinions about what ear drops to use, as I can get ear infections dry from my allergies, and will not spend the night away from home without a bottle. I like neomycin to kill the bacteria and hydrocortisone to kill the pain. I am not trained in medicine, but I like what works for me. When I run low, I pick up a couple of bottles on a Cozumel trip as it's easier than seeing a doctor for such a simple need.
I had to go to doctors two or three times for wax removal decades ago, until the last one told me how to do it myself. He had me add baby oil, mineral oil, or similar (I think it was a baby laxative sold at the time), plug each ear with cotton balls, then use an ear syringe and warm water to remove the softened wax the next morning. There seem to be a number of packaged kits along those lines now.