I'm really worried because I've had gastritis since 1998, but these past two weeks have been different. I've been feeling this nagging burning sensation in my upper chest that spreads to my upper back and sometimes even to my arms. It gets worse when I'm lying down in bed, making it quite uncomfortable. I've tried taking some antacid tablets and they worked a bit, but the pain is still pretty intense and annoying. Could this be something more serious, or is there something else you'd recommend I do to get this under control?