How Long Should An Ear Infection Last?

How long should an ear infection last? I have had 1 for 3 and a half weeks, 2 weeks ago I went to a walk in clinic doctor who prescribed me cefprozil for a week and after the week there was no improvement in my right ear. I have not been back to that doctor since. It feels like my right ear is plugged and that there is pressure there. When I swallow my ear feels or sounds like what a speaker would sound like if it was hooked up to a microphone and wind blew into the microphone for a short period. What should I do?