I had a similar problem once (trouble swallowing at times but accompanied by chest pain) and my internal medicine doctor did a scope and said I had a stricture caused from reflux, and a small sore. They put a hose down my throat to force it open and it felt a lot better afterwards.
I agree with the last comment, just go somewhere else. I don't understand these doctors that don't do the tests that you want, it's ridiculous.
A number of things weaken the LES, including caffiene, alcohol, chocolate, and peppermint. I haven't heard of antacids weakening it.
I wonder why your GI doesn't want to do a scope? You may want to consult with another GI for a second opinion. Back in 1991, after several years of serious, undiagnosed illness, I insisted on a scope, over my family doctor's objections, and the scope immediately revealed a bleeding, raw esophagus, with "long" Barrett's. I was misdiagnosed for several years, so don't rely on only one doctor's opinion if you are not getting relief and are not comfortable with her/his refusal to recommend a test that you think may at least rule OUT issues, if not find out what is actually wrong. Had I been scoped two years earlier, I may not have gone on to develop esophageal cancer and require a complet esophagectomy in 2001. You need to be your best personal advocate and push for additional tests if your situation isn't improving.
Best of luck.