Wow. You've had almost every test imaginable. I bet your exhauseted by this. I can relate to how you feel. I would ask you since you have had a complete physical work-up. How is your mental state? Are you stressed out or have you had constant stress for a stretch of time? Are you feeling overwhelmed? Do you think that maybe this is the area that needs help and it is manifesting itself into physical symptoms?
I also recently have had a bunch of physical symptoms like you have described. I have taken a closer look at what has been bothering me and have come to the conclusion that I am really stressed. Kids, hubby, work especially. I am making the necessary adjustments in this aspect of my life and I'm noticing my physical symptoms are going away slowly but surely.
I think sometimes it is easier to deal with physical symptoms than with these tougher mental/emotional issues. I have recently started a journal to help me understand what I am feeling physically, eating, thoughts. I want to know what gets this pattern started and how to prevent it.
I don't know if this helps. But keep on trying. You'll find a solution...