Hi, I'm surprised your doctor asked you that just like that

odd. Anyway, my doctor did the stool sample first before any xrays. He put me on medicine even though they were fine. You don't mail it back to the lab. You have to bring it in within a couple hours, that's what they told me. Call your doctor and see where and when you're supposed to bring it so they can get an accurate reading.
Next, if that's normal, my doctor sent me for an Upper Gi, then later a ct scan, colonoscopy, and endoscopy. They have to check everything before they can tell you that you have IBS.
Also, my pain is on the left side, sometimes under my ribs, sometimes lower. You normally would have to have irregular bowels which you haven't mentioned. If you just have a pain it might be entirely different. Also, your colon is over there but lower I believe. That's where mine was so they wanted to make sure that I didn't have any sort of problems going on there

Maybe it's an ulcer or something. Try eliminating some foods too...for me it's fast food, grease, etc.