You will need to have a physical exam as part of the admission process to get into a nursing school. When you list the medications you are taking on the medical history form, the person examining you is going to have a good idea what your medical problem is. Their main goal in performing the physical exam is to determine if you are able to physically and mentally perform the work of a nurse. If your Crohn's is under control with treatment, go for it. I don't think that you need to elaborate about being hospitalized with the nursing school interviewer(s) unless they notice it on your medical forms and specifically ask you about it. Anyway, there's no way of knowing when (or if) you're going to need hospitalization again, so I wouldn't even bring that isssue up in an interview. Deal with it when and if it happens.
I was hospitalized and had to have a major surgery for cancer during my fourth semester of nursing school. My instructors were totally accomodating and helpful about it. I was allowed to make up the clinical days I had missed by going to a couple of extra clinicals with one of the other groups of nursing students from my class. Some of my fellow students were assigned to me when I was in the hospital (I agreed to it). I worried for years that I would have problems getting jobs and being allowed to have my employer's medical insurance benefit because of the cancer. That was 30 years ago and it hasn't been a problem--ever. In fact, the cost of my radiation therapy was picked up by the medical insurance I got as a benefit through my first employer. You're going to find that nurses are going to understand your medical problems better than any other group of workers and will be very accomodating for you. If you're worried about the stress, talk with the doctor who does your nursing school evaluation. There are ways to ease into the nursing role without subjecting yourself to overwhelming stress that you may have read about on some of the forums. It will just take a bit longer to get settled in the RN role is all. I worked as a telephonic nurse where my day consisted of sitting down for 8 hours and talking with people on the phone and documenting those conversations on the computer. No stress. I negotiated for the job of just doing the written patient care plans
and some other required documentation at a nursing home once. Nice job. Again, no stress. I've also worked in the thick of busy hospital units where the stress was sky high.
3.0 is a pretty good GPA. You wouldn't be working with preceptors until you are being trained at a paying job. In nursing school you will be working with instructors and other students. Good luck, sweetheart. Don't let your medical condition prevent you from being the nurse you always wanted to be.