No, it does not really "turn into" Crohn's, but what happens is that you had Crohn's all the time, but just not with signs and symptoms that would point to it. There are a number of folks here who were certain they had UC, but later after colectomy were diagnosed with Crohn's.
Not sure why a Fleet enema would cause inflammation like that, but next time you are scoped, don't use it. Just use plain tap water instead. I open the Fleet enema, throw it out and refill the bottle with plain tap water.
Still, some rectal cuff ulcers do not mean it is Crohn's. But, say they assume it IS Crohn's, then that would mean there are more drugs you can try to treat it (there are more drugs approved for Crohn's than UC and most often the insurance company will only pay for FDA approved treatments). Case in point: I use Simponi for my enteropathic arthritis, and my pouch and cuff have never looked better. Same thing when I was on Humira for the same diagnosis.
Jan