Hello. My goal is to help you find an answer! Augmentin is a really good choice. It might be overkill though. You could probably get away with just the amoxicillin component of it instead.
Other options would be azithromycin or a cephalosporin like ceftriaxone.
Any complications because I'm a diabetic?
When should I expect to feel markedly better from the amoxicillin?
No problems with diabetes. However, you doc better be sure its an inner ear infection and not outer. Diabetes are prone to otitis externa and it requires different antibiotics. You should already be feeling better from the augmentin. Are you?
The amoxicillin should continue it. I would treat for 10-14 days total.