Welcome to HCM,
Your symptoms are suggesting me that you may be having viral infections or allergic laryngobronchitis.
As you are having infection of the larynx
you are having change of voice and hoarseness
of voice.Chronic infection of the respiratory tract
is leading to all these symptoms like post nasal drip
, terrible cough
As you have tried may drugs and antibiotics, I would suggest you
1.Steam inhalation with Vapocaps
3.Blood Absolute eosinophill count
4.Skin prick test to identify any allergen causing these symptoms.
These investigations will help us to find out the cause for symptoms and then we can plan proper modality of treatment.