Why am I haveing stomache cramps?

I recently changed my whole routine I am trying to quit smoking (using the patch) and I heard that instead of picking up a cig. i should pick up a water bottle and now I am exercising I used to drink coke all day seriously all day now its water and I started eating breakfast and lunch regularly and now i cant go... but yet I am gy I went to the Dr. but they made me drink this god awful white lotion textured mixture that would gag anyone and now I am waiting for my next appointment so I can get the results back. is it just with drawls or could there be something more I even started eating Yogurt! and other healthy foods that are designed to make you go, can anyone relate?- I am 24 I shouldnt have IBS right?