I have had what I guess are full on flares, where the entire flare follows a pattern. I have also had mini flares that are very short--these do not always follow a pattern. I have also had varying degrees of flares where symptoms of one flare are not as painful or severe as another. What makes these different, I have no idea. Sometimes, I won't recognize I am in a flare until the symptoms get worse, if that makes sense.
I think over time you learn what your flares are and it kind of comes together. It took me a couple of hard flares to discover the pattern. This last flare I have been in has been different, but I am REALLY hoping it is because I got started on Remicade and that it is working!
I agree with Mike that this disease is different for everyone. There are also so many different symptoms and things that can happen with Crohn's that it can really throw you for a loop.
Best of luck with your health and baby #2!