Sometimes a diagnosis can change because the current information (biopsies, blood tests etc) are not that clear or inaccurate. It is possible to have both Uc and Crohn's but it is very rare. There is a condition called Crohn's colitis and this basically means that you have Crohn's but it is limited to the large intestine.
Hollipher, personally to me it sounds like you need some different doctors. Ones that have you in their best interest. It's crazy that a doc would put you solely on pred and not prescribe any other sort of med regardless if it's Uc or Crohn's. The medications taken by someone who has an IBD is designed to reduce the inflammation in the intestinal tract. Once the pred is gone, there is no steady stream of medication to prevent that inflammation from coming back. One can not be on pred for long periods of time because it can cause other issues such as bone loss, bone necrosis and adrenal gland issues. Many doctors are quick to prescribe pred when a flare can be tamed other ways that are less damaging albiet it may take longer. Really, I think you should find another doctor or make another appointment and discuss this in more detail.
How can a diagnosis go from Uc to Chrohns? I have just been diagnosed with both I think. I need a second opinion. I am on prednisone and I don't like this at all..I know they are other options out there. I can't go to the bathroom on these either..
So the 2nd doctor is saying you don't have UC because the first doctor messed up and didn't prescribe anything? Does the new doctor have copies of all your records? How are you doing?