could be IBS. i had that same problem when i hit 30 for some reason. felt a gurgling sensation on my sides, when i got nervous it would come, mostly at work, did all their tests and like you came back normal. I then was refer to a gastrologist who said might be IBS so he prescribed me amitriptyline for stress part and xyafin to help harden stool. the results were great i could hold it in more so then before. Now three years later he took me off the xyafin and prescribed me Chlord/Clidi which has greatly harden my stool and i feel like my old self. still take the amitriptyline every night before bed.
Does it seem to you that it get worse after you eat pizza or had any food with gluten in it
Do you feel bloated at any given moment of the day?
My husband has Celiac Disease, it runs in the family. He never loose weight or gain, until he was diagnosed, he cut off the gluten out his diet so he gain weight a little bit. He had bloating, always running to the toilet.
Ask your doctor about auto immune deceases, sometimes hidden ones are hard to find.
Hope this helps
Good luck and I'm here to help