Congratulations for being a caring teacher. You would not believe how many teachers are more concerned with their agenda than a student with an illness such as Crohn's. I don't know if it is just from ignorance or what.
My son has dealt with Crohn's for many years. He had problems when he was very young, but it really flared up in middle school. He is in high school now, and they complain about how often he is absent from class. I do know he hates to miss class because he has so much to make up when he returns. Some times he will miss one class because he spent too much time in the bathroom and is embarrased to walk in so late and have to deal with all of the explaining. He has had numerous "accidents" at school, but they seem to come and go. He may go for a few months without any and then...bam, it will start acting up again. When he started driving to school it helped because I did not have to leave work to take him home if he was feeling pretty bad. Also, it is a difficult problem, because Crohn's kids do not need to go to the doctor every time they feel bad. Believe me, parents could not afford it either!
I do know that the teachers that have been understanding with my son are highly esteemed by him. I know several others in the forum mentioned the homework issue. Yes, that is a BIG problem with my son, too. It is hard for him to keep up with his homewwork when he is feeling ill a lot.
People just do not know what it is like living with this illness, and yes, everyone is different. Just because they seem happy and okay does not mean that they are. I think Crohn's kids get very good at acting at an early age. They do not want to seem different.
Just think...would you want everyone at your work to think that you have problems "pooping in your pants"? ANd that is just one small part of the problem...
Hang in there, and privately let your student know that you care and are there for them...