I cannot answer your question re what is causing your LPR but I do know that the vagus nerve can cause problems for many.
I am going to post a link here for you that may provide you with some decent info re LPR:
http://www.voiceinstituteofnewyork.com/silent-reflux-laryngopharyngeal-reflux-lpr-is-ubiquitous/
To help understand how the vegus nerve affects our whole
body you need to know there are twelve pairs of cranial nerves present in the
human body system. The tenth pair of cranial nerves is known as vagus nerve.
This nerve is also known as the wandering nerve, (Vagus in Latin means
'roaming' or 'wandering'), since it travels from the medulla of the brain till
the viscera (or abdomen) in a zigzag manner. The vagus nerve has several
branches which connect the ears, larynx (or voice box), heart, lungs and the
stomach. One of the main functions is to transmit information regarding the
working of the organs to the brain. It also governs reflex responses of the
organs. Other functions include regulation of the heartbeat, breathing,
controlling movements (or contractions) of the muscles, and transportation of
chemicals etc. Selective stimulation of the nerve is a therapeutic method to
treat depression and epilepsy. However, over-stimulation of this nerve can
disrupt blood circulation and even cause the individual to go into coma.
I am sure you will be hearing from other members of our forum who have personal experience with LPR. I wish you the best and hope you find out what is causing your LPR.