Hi, thanks for using healthcare magic
can occur for a number of reasons. It is also known as laryngitis
which is inflammation of the vocal cords.The most common reason is infection such as a viral infection.
It can also caused by (1) allergies such as a post nasal drip
associated with allergic sinusitis
(3)over use of the voice (4) excess alcohol use (5)GERD
(gastroesophageal reflux) (6) some medications such as asthma
Since it has been going on for such an extended period , it would be best to be evaluated to determine the exact cause.
I hope this helps