It is good that you said about GERD
Now the next thing to be looked for is Nasal and sinus infections.
or allergies earlier you had or you have at present.
You must consult an ENT specialist
.And get done a CT scan
of nose and paranasal sinuses
to rule out any disease in the sinuses and any anatomic abnormality in nose .
It is the infected or allergic nose from where the infected material trickles down the throat and irritates the it.
If in doubt do reply.