Hello and hope you are doing well.
The Eustachian tubes can get blocked due to infections of the throat, which can give lead to a feeling of fullness in the ears. This can also result in infection of the ears. The blocked ears can be opened up by the valsalva maneuver, where air is blown into the cheeks against a closed nostrils, this sometimes helps to open up the tubes. Steam inhalations and warm salt water gargles can help clear the tube. The tubes can also be blocked in Eustachian tubes dysfunction. The blockage can be intermittent. This needs surgical intervention.
Hope this helped and do keep us posted.