Abdominal pain. It be please suggest.

It's been a year to my sister's marriage. After marriage she had loose motions and abdominal pain which resolved in few days. After 2 months she again started having abdominal pain. We went to the doctor and had medicine then again it resolved. And from this January she again started having abdominal pain and chest pain. She had endoscopy done in which there was HPylori infection. She then had a course of antibiotic which doctor prescribed. But now it's not getting better. She is having constant abdominal and chest pain. There is pain when doctor press on lower abdomen.There's no blood in stool. No constipation no diarrhoea. Actually due to her teeth issues she had to take painkillers from 5-6 years. Doctor has advised colonoscopy. We are going to have her colonoscopy done this Monday . What can it be please suggest.