I'm sorry you are going through this and I hope you do well.
Your situation is quite complex and as you can imagine, no doctor can give you a diagnosis or treatment over the internet. If someone says they can - they are lying to you to make money.
Instead, I will give you some recommendations to discuss with a physician who knows you and your history well, such as your primary care physician.
Many of the more serious disorders seem like they have been ruled out by your work up detailed above. IBS (irritable bowel syndrome) can present as you describe and is resistant to many treatment modalities. It is a challenge for us as physicians to treat IBS. You as a patient can change your diet to help:
Your doctor can try a few of the medications listed below and also psychotherapy which as been proven to help IBS.
In summary: Lyrica, Amitiza, Elavil, and psychotherapy are a few of the medications you should ask your primary doctor about.
Hope this advice helps!