I Have Had Chest Pain For The Past Few Months.

I have had chest pain for the past few months. I spent two days in hospital in early feb. Had a stress test and other tests done. Didnt know what the cause is, not related to my heart. Still happens, mostly upper chestnsometimes left, sometimes right side. Cant sleep at night, even staying up extermely late the night before or even taking advil pm. Wondering what could cause this.... Husband believes it is stress related.