Something pushes threw my mom rib cage under her breast short of breatheshes had an mri and ct scan and they cant find anything what could this be?

Short of breath: I am missing information to understand the issue well. I assume a MRI and CT was normal of the chest. If that is the case then lung issues seem to not be the problem. I would guess that abnormal rib movement is causing pain, as a result, her breathing is abnormal to prevent having pain. If that is true an osteopathic doctor who treats ribs ( not all of them do) is your best help.