puppy with an itch!

Hi guys, long time follower on the boards, first time poster. I had a question about my dog. So my GSD is three months old, and she's an absolutely amazing dog. I noticed a few weeks ago that she had been itching herself. As time progressed, i noticed her itching and gnawing on herself more and more. I've checked her several times thoroughly and have seen no evidence of fleas, or flea dirt, or blood, or scabbing. I then thought of allergies and tried reading up on allergies and dogs and I read to try benadryl. I've given her benadryl (childrens because target apparently was out of regular)) for the past 3 days, and havent really noticed a change in her scratching. Are there any other suggestions as for as allergy medications go? I dont know if this goes hand-in-hand with the scratching, but also the inside of her ears are red and kind of inflamed, but i havent noticed her scratching her ears or anything at all. any help would be appreciated, thanks!