How To Treat Plugged Ear?

I have had a plugged ear for 2 weeks. Went to doctor and prescribed ear drops for external ear infection. However, my ear usually becomes plugged everytime I insert drops and stays plugged. It hardly ever is unplugged throughout the treatment. My doctor even switched ear drops but my left ear stays plugged. Tried yawning, swallowing, decongestants, flushing with hydrogen peroxide (nurse did this a couple of days ago). Still plugged. Can you help? I am 65 and heading to Hawaii on Thursday in a plane. Worried about my ear.