Vinager.
No, I'm not kidding.
We use apple cider at the shop.
Wash him with dish soap (seriously, toss the doggy shampoo) you need to get the grease and dander off him and that requires Dawn. If he's super greasy and funky, go for two suddsings. On the second suddsings, soak him down with vinager, scrub it in and let it sit for five minutes or so. One other protip, avoid scrubbing really hard or really massaging the skin. You want to let the soap do the work on the degreasing. Massaging the skin is just going to stimulate the skin into producing more oil.
He'll smell like a salad, but it will get rid of the yeast.
After that, keep a regular bathing schedule. The whole 'too many baths drys a dog out' is a myth. Aim for every two weeks. If you get him going the full two weeks without funkyness, you can stretch it out to three. Keeping his hair coat and skin clean will go a long way to making him feel better.
Second, ears. Clean and medicate. I recommend a mix of 1/3 green alcohol and 2/3 apple cider vingeger. The vet will likely give you otobotic (spelling is probably wrong there)
Flush the ear with cleaning solution, basically just pour it in and fill it up, swish around and then let him shake his head. Use cotton balls and qtips to wipe it out. Keep going until your not getting gunk. If there is a lot of gunk, you may need to reflush. You are likely to end up with some bloody cotton balls and he's not going to much like it, but you want it clean.
Then put in the ear drops. Go easy on it. Really, just one drop. Massage the outside of the ear to rub it in.
You want to do the ear meds daily (whatever the vet recommends) and do a good clean every three days or so. Don't clean the ears everyday. You want to give the meds a chance to work.
Along with bynadryle and food changes, you may be able to clear it up.
You also may just have a chronic issue. Some dogs are just natural greaseballs and some dogs just get ear infections, and it gets more chronic as they age. If that's the case, learning to deal with it and being in a position to catch it early and treat it before he gets uncomfortable is the best bet.
We have a few clients at the shop like that. One in particular, Teddy, is finally on a routine that really works. It took years to convince his idiot owner to stop changing things up everytime he showed up and doing all this random homeopathic crap. We've gotten him to the point were a good dish soap bath (mostly without vigeger anymore) every month and regular ear cleanings keep most of his issues at bay. Plus, we are now catching the infections before they get bad, and he can get treatment.
He's in much better shape.
Mind you, he's still dumber than a box of rocks and his owner is still an idiot, but he doesn't stink so bad and he can actually do more than sit around and scratch himself these days.