thanks for your query
History seems that it could be a glue ear or middle ear effusion
due to Eustachian tube dysfunction
Better to consult ENT specialist
and examine. if so you need gromet insertion.
Mean while take anti histaminics like levocet, mucolytics like acetylcysteine
Do Valsalva manure i.e. do puffiness of cheeeks with closer of nostrils and glottis. will increase pressure in nasopharynx in turn help to openup Eustachian tube.
Thanks a lot. take care.