How can i help my sister-hypoglycemia

My sister has 30 years old, and she has been with this problem around a year, since this started she has gain 15 kg. The sugar in her blood goes down till 20 and now even when she sleeps.
We are from El Salvador, Central America and she is hospitalized now in our social security hospital but they have made several exams that didn't came back with a clarified diagnosis. The TAC doesn't present anything anormal. The glucose test confirmed that she has an insulinoma but they still dont know where.
The options that they gave us its to do a surgery, and removed a part of the pancreas or even the pancreas it self, but this doesnt ensure that she will be healed. She can be hypoglycemic and diabetic at the same time after this surgery.
Its there any other test that can be done or some way to find out were the insulinoma is?? even if is taking her to another country its there some institute or hospital where they are specialist in this cases?