Unfortunately, there is no quick fix when it comes to recurrent ear infections. Ear infections can be as a result of multiple factors including ear shape, ear canal size and shape, humidity, temperature, normal flora or a combination of these factors. So unfortunatly, you may have a problem that continues to come back despite treatment. 

You can use vinegar to treat recurrent infections but there are a few important points you must know first

1) BEfore using the vinegar, you must be absolutely sure that the ear drum is intact. Using vinegar with a damaged or perforated ear drum will cause ir-repairable damage to the ear and possibly deafness

2) Never use undiluted vinegar. It must always be mixed with equal parts of water. Use warm water so that it not uncomfortable. You can use white vinegar or apple cider vinegar

3) Us a syringe to put the solution into his ear and make sure you flush the ear with about 100ml of solution at a time. Do not get any in the dogs eyes as it will cause severe irritation

4) Once you have washed out the ear, allow the dog to shake his head to get rid of the excess and then dry the parts you can see with some cotton wool, never an ear bud

5) Make use of vitamin c tablets daily for him (human ones are fine). They help to decrease inflammation in the ear.