Hi... Sorry to hear that you have been diagnosed with Crohn's. It's not an easy disease to deal with at any age and being young sure doesn't help. I hope that your friends and family are being supportive and trying to help, although they don't understand what your going through.
If you are finding the side effects of the pred hard to deal with there are other meds you can try. Maybe try and speak to your GI if they can suggest anything.
I hope for you that as time goes on it gets easier to deal with. Try and stay positive but don't forget that it is hard to deal with from time to time. Don't be to hard on yourself, we all have our down days but you can get through this