I know how you feel. I, myself, tried to tell myself I was okay for so long. I continued to lose weight and had diarrhea and pain. Everyone knew I wasn't okay, but the doctor kept running tests that kept coming back normal, so I "believed" him. Not good. After a year of all of this, I was diagnosed with crohns and am finally feeling better.
Anyways...as for your friend, I would say, be a good friend. Try to get her to go to a doctor in a supportive way. I'm sure it's hard as a doctor to be a patient. I am a teacher and they say that "teaching teachers is the most difficult thing to do." Check on her and see if there is anything you can do. It is ultimately her decision in the end...she has to get the help she needs, but let her know that you are there for her!
Good luck and keep us posted!
I agree with the ohers who have answered you here, if you feel you have a close personal and trusting relatonship with this friend ask if she would be comfortable talking about her Crohn's with you.
Listen to her and then encourage her in a kind and gentle way to seek help as you are worried about her.
I pray she will respond to you.