My girl Fannie was the queen of ear infections. She also dealt with yeast problems on her feet and chin. First thing I would do is find out what is causing the infections. Bacteria or yeast. If it's yeast I would lean toward your issue being leaky gut syndrome. This is the problem we had with Fannie. She was around 10 when we finally figured it out. We changed her diet and used Nzymes products designed to help with these types of issues. These helped a lot, but we were never able to completely clear up the issues. I think it was because she had been dealing with it for so long.
Every dog is different when it comes to food. Sophie eats premium grain free foods, no chicken, no potatoes. The one time she had food with potatoes, she got the only ear infection she's ever had in her 6 years. On the other hand, Brooks eats Eukanuba Performance 30/20, which has chicken and corn. He has the cleanest ears I've ever seen.
Labs are very stoic, but if Chief is in a lot of pain, it could definitely cause behavioral changes.
You can check these regarding leaky gut.
Dysbiosis: Does Your Dog Have Leaky Gut?
Canine Allergies and Your Dog's Health | Whole Dog Journal
Leaky Gut in Dogs. - Holidays4Dogs - Home Boarding for Dogs