GERD Rating

I was rated at 10% for GERD when I submitted my diagnosis to the VA. I take doctor-prescribed medication for it, and my condition is severe enough that I experience acid reflux when lying down, which has led to documented damage to my esophagus according to the VA. How can I pursue an increase to 30% for my GERD rating? What additional evidence should I submit, and would it be beneficial to consult an outside service for assistance?