Last night I bent over to pick something up and my left ear popped and then started to hurt, could this be a sign of an ear infection?
More likely pressure. You likely had an unnoticed closure of your eustachian tube that reopened to allow some air into your middle ear space. But this should not produce continuing pain. An office exam can separate the issues that will self correct vs the possibility of an ear infection that needs treatment.
Ear pain. You may have had a cold. By ending down you may forced fluid in your middle ear causing pain this fluid called serous otitis maybe a precursor for infection. Have it checked out.