Why does my ear keep getting blocked?

You said ear so I assume it is one ear. Has your PCP found ear wax; which is easily removed in their office? And what has you PCP found as to sinuses? Sinusitis or blockage of the sinuses can produce fluid accumulation in the ear. Once you and your PCP know the cause of the ear blockage, treatment ensues.

The outer ear canal (external audotory meatus) is lined with a skin that has glands that secrete a waxy oil (ceruminous glands) this naturally flows out and serves to portect and allow sound to bounce into the eardrum. This wax accumulates and can be pushed back if you stick your finger or anything else in your ear causing a blockage. It happens more with age, dare I say that? Get checked!