I have had the same experience with abdominal pain and testing, with no answers. I've had doctor's suggest that it could be coming from my back, and others say that it is from my muscle spasms.
Most recently, when I pointed out where the pain is to a neurologist a few months ago, she said "that is a thoracic dermatome", meaning that the pain was wrapping around the path that a nerve from my thoracic spine follows. She did nothing for it, as she was seeing me for something else which she decided I didn't have and kicked me to the curb.
Sorry if I sound a little bitter; chronic pain can do that to me sometimes, especially when combined with lack of answers.
Good luck, and take good care of you.
Kathy
Let me know if you find anything out. I also suffer from back and abdominal pain; however mine is mostly at night when I'm trying to sleep.