If she's had the endoscopy that must have ruled out a number of problems including polyps.

Which medications do they have her taking now (apart from the B12 and the Vitamin D)?

When you go to the doctor or the hospital do they give you copies of the results of the tests? If so, do you know what her B12 level is?

Has her Thyroid been tested?

Does she have gastric reflux?

http://www.healthdirect.gov.au/gord-symptoms
Gastro-oesophageal reflux - Symptoms