Can I ask how often you're having diarrhea? I'm asking because it might be related to food allergies. If you're having problems with gluten or dairy products it can irritate your digestive tract causing pain and diarrhea. Corn can be very hard to digest and I think most of us have it come back out in whole pieces, this is not uncommon.
How you been to see your Dr yet about your symptoms? If not, I recommend you do.
Yes, this might be IBS but only your Dr can tell you after doing tests. If your family Dr can't figure out what's going on he/she may send you to a GI specialist.