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!