Suffering From Intestinal And Stomach Bloating. Normal Test Results. What Could Be The Reason?

Hi, I have been suffering from severe intestinal and stomach bloating for the last six months. Prior to that, I had severe heartburn for 6 months which changed to bloating when i was admitted to a hospital for a renal colic and was administered Morphine. I don't know whether there is a relation to bloating and morphine triggering it, but my doctors have tried everything possible to diagnose what the cause is. Here are all tests that were negative
a) celiac, parasites and h pylori
b) upper endoscopy
c) an ultrasound (liver is a little fatty but my gastroenterologist told me that it is very minor and losing a few pounds and eating less fatty food with solve the fatty liver issue. I have lost 10 pounds since then. I am 152 and 5'8" and 29 years old). No gallstones showed up either in the scans.
d) a MRI (for kidney stones though)

I have tried all possible food combinations and diets. But nothing helps and everyday after 12 pm my bloating starts and continues until dinner at 8/9 pm. Some people say its aerophagia but i don't agree because on occasions it start much after i am done with my meals. My doctor put me on probiotics, but that did not help either. Beano was helpful for a couple of days but not after that.

What do I do and what do you think is the cause of this bloating?