Hi thank you for posting on HCM; I understand your concern, Because she gives a long history this is likely due to recurrent/ chronic gastritis with no major gastric ulcers as all the tests were almost negative. (hope she has already undergone Upper GI endoscopy tests). Has she been treated with Antibiotics with anti gastritis treatment? Because Helicobacter Pyelori is a bacteria which causes recurrent gastritis in some people. She also should have taken Proton pump inhibitors like omeprazole or esomeprazole for adequate period continuously even though symptoms get improved after few days of treatment. Burning sensation of stomach due to gastritis can be treated by surface anesthetics which are included in some antacids syrups, eg: Mucaine. Psychological stress also a well known factor for increased gastric acid production and should be manged with( if having) by meditation and relaxation techniques. Hope the answer is helpful.