What Causes Hearing Loss In Right Ear?

Hi,I have had a septoplasty 3 months ago and have a slight loss of hearing in the right ear. The ENT Dr. tried to drain the right ear,no fluid found. He then cut inside preparing for a drain. He found no fluid and does not know why I have the hearing problem . it sounds like I am talking inside my head. He also said there is no such thing as a npost nasal drip. Could this be a result of the septoplasty? Thanks Joe