Could Constant Abdominal Pain Be The Symptom Of Irritable Bowel Syndrome?

Hi, I ve been having a constant abdominal pain, mostly localised in the middle. It s been over two months and now it is almost constant. It hurts when I walk. I went to see my doctor but he said it s IBS without even asking me any further questions, not even examination (I said that I have constant abdominal pain and he said that it s IBS). He prescribed me Meveberine and it s been three weeks but the pain is still there. I m going to see my doctor on Friday. Both of my grandfathers died of cancers: one of stomach cancer (aged 75) and the other of colon cancer when he was 40 years old. I m 28 years old female. I rarely drink and don t smoke and I ve been vegetarian for 14 years. Is there anything I should ask my doctor, demand an examination? I guess I need a second opinion as I am worried. Thank you.