Did you get tested for H Pylori? It's a very simple breath test. I've told my story of how I got GERD. It was by taking Advil at night, for pain from my tripping accident when I and injuring my left side, and not staying upright for at least 1/2 and hour after taking it. Then sleeping exclusively on my right side so the acid started seeping up into my esophagus.
It goes to show you, there are many causes of GERD.
Get tested to rule out H Pylori.