The good news is that ear infections often show improvements after less than 12 hours of medication. My son (3) was just diagnosed with a dual ear infection on Saturday afternoon, and by that night, 6 hours after medication, he was amazingly different, coughing less, sneezing less, playing, and SUPER hungry - I think he ate all day long on Sunday.
You may want to think about frozen fruit, juice bars, or slushes, which wilol help to soothe his throat. Make food you know he likes, as he will be more apt to eat it. It will pass and he should be back to his normal self soon.
One additional note - if you don't see improvement by 1/2 the time of the meds (usually day 5) contact his pediatrician. My daughter had an ear infection in November that lasted forever - then we found out (after 10 days of medication and two more days of waiting to get her into her normal dr) that ammoxicillian doesn't work for her. They put her on Omnicef and she was better in a matter of hours.