Please continue to follow up with the ENT and audiologist to make sure that she gets the proper treatment. Hearing is so important for speech and educational development.
I guess your abbreviation "cdHL" means "conductive hearing loss." I assume that the ENT saw a fluid build-up in the middle ear. This often happens from Eustachian tube dysfunction. This is the tube that runs from the middle ear to the back of the nose and is responsible for draining the ear. Antihistamines, like betahistine, have been reported by some to help with Eustachian tube dysfunction as they can decrease swelling in the nose, which can, in turn, allow the Eustachian tubes to open and to drain the middle ear. However, many studies in the ENT literature have proven that they don't work. What might be better are nasal steroid sprays. This would only help to improve hearing in the right ear alone, if that ear does have a conductive hearing loss from a fluid build-up. For the left ear, her best options at this point are a conventional hearing aid or even a bone-anchored hearing aid, which is placed in the operating room by fellowship-trained ear surgeon (neuro-otologist). General ENTs do not do this procedure generally.