Hi hearty and welcome,
While stress causes a lot of ailments, doctors have not proven stress to be a cause of GERD. Your behavior while under stress may cause heartburn and reflux (smoking, alcohol consumption, sleeping habits, eating habits/certain foods (ie. I love chocolate when I'm stressed but is bad, bad for my GERD)). I know it is stressful but you may have to go down the list of PPIs to find one that works for you. They all have a different formula and even though they are made to treat the same thing doesn't mean they all work the same on everyone. I am on Prevacid now but only after trial and error. Don't give up and try to keep yourself healthy... and keep us posted!
IBS, Diverticulosis, GERD, Cervical Disc Degeneration
"If you don't like something change it; if you can't change it, change the way you think about it" - Mary Engelbreit