Good Morning and welcome. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
Often, these ear infections become chronic because the scar tissue caused by the infection allows the bacteria more places to hide. It also is associated with a suppressed immune system. For this reason, I recommend PetAlive C Caps which is a holistic immune stimulant to help the body fight this off. LINK
Preventative maintenance is also recommended which can be an ear cleaner such as Epiotic from your vet or Swimmer's Ear available at the pharmacy over the counter that is applied every 3-4 days. This dries out the ear so the bacteria and yeasts cannot grow. This can be very effective against ear infections.
Yogurt has been known to help with yeast infections but most ear infections are a combination of yeasts and bacteria and will not help in Max's situation.
Allergies are a possibility that cause the infection to start by the scratching and will respond to Benadryl at 1 mg per pound every 12 hrs.
Try these on Max to see if this will help him past this very difficult condition.
This LINK may help.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please Reply so I can clarify for you
Sincerely, XXXXX XXXXX