The first time this happened to me, I went to a gastro doctor who teaches at Stanford. He was clueless. When I found the problem, he refused to believe me.

I would not rely on a massage therapist. Most do not have the medical knowledge to find the problem. Massage therapists have their place but not with this kind of an injury.

With my physical therapist, she did somewhat painful myofacial release and very gentle traction and mobilization. This kind of injury will not image very well. You need someone with good but gentle hands.

Have you considered whether you may have a hiatal hernia to go along with your back injury ? The fall could have jammed your stomach up into your diaphragm wall. Do you know how to do heal drops to resolve a hiatal hernia ?

Do you have access to a physiatrist (Physical Medicine and Rehabilitation) ? They are often good at these non-orthopedic but skeletal injuries.

My best to you.