14 m.o. GSD One ear down for the last month

Question
Hi, I have a 14 month old GSD male whose left ear has been flopped down for about a month now. In general, both of his ears were always up, but occasionally the left one would flop down...we would say "Bad reading on the ear-ometer!" and it seemed that as soon as he had a nap or a big drink or whatever, it would pop back up. Now it has been down for the last month or so, though it will go up momentarily if he is outside and really interested in something, etc. There is no evidence of an infection or other medical ear problem. He is on Nutro Large Breed Lamb & Rice Adult, now. I don't know if I discontinued his puppy food too soon, or what. He does seem to be still growing. I don't really consider taping/propping to be a practical option as he has a very active life with his "sister" shepherd mix - I can't imagine anything staying in place. He's the best dog we've ever had, sweet and smart, but it would be nice if that ear would go back up. Back to puppy food? Supplements? An extra piece of cheese?

Answer
No, no, and no.  Perhaps you stayed on puppy chow too long.  It is counter intuitive, but too much calcium in the diet is worse than too little.  And good hips are much more important than ears that stand up for anything except show dogs.  Neutro is highly respected although I don't know if it is based on anything except its price and casual observations.  I would continue the adult Neutro and nothing else and hope for the best.