Abdomen Pain

42 yr old male.  Dx with Barretts Esoph, GERD and High Cholesterol (mild).  Dx with Barretts over 5 years ago put on Protonix 40 mg 2X day then lowered to 20mg 2x day.  Endoscopes done yearly for first five years now on every 1 1/2 year all have been fine no progression of barretts and all biopsies fine.  Next one is on dec 20.  Colonoscopy done in 2009 due to family hx everything was fine..small polyp that was removed.  Have had on and off left side (more lower) pain probably 1 or 2 on scale of 1 to 10 for over three years of and on  No real change in bowels (varies but nothing consistent in terms of diarrehea or constipation), no blood in bowel movements no other issues. Had Abdominal Ultrasound three months ago and it was normal...Doctor said it is either gas or abdominal wall pain (pull) and said no further investigation necessary doesnt want  to have me exposed to radiation...he felt my abdomen no masses felt....over weight and diet has not been the best so starting to excercise...when I do exercise or walk around abdomen does not hurt..any advice/suggestions?  Could it just be gas or IBS?