Thanks for the query.
If she has gone to all doctors and has also done all possible investigations then you will need to take her to a Psychiatrist
.She might be most probably suffering from Psychogenic pain .Psychogenic pain is a pain disorder associated with psychological factors. Some types of mental or emotional problems can cause, increase, or prolong pain.Headaches
, muscle pains, back pain
, and stomach pains are some of the most common types of psychogenic pain.She will need detailed evaluation.