Hey there. I'm new to the forum, but not Crohn's!
My best advice is work closely with your doctor, eat healthy (no fast foods or fried foods) and try to exercise if you can. I was on a very high dosage of Prednisone when I was young. It increased my appetite greatly (which also made me gain a lot of weight) and yes I did experience pimples (facial and on my chest/back) It's just something that happens while taking a steroid. I didn't exercise then, but it may help curb the appetite and your digestive system.
Stretching helps a lot too such as Yoga (i never tried yoga but i hear it does great things)
Everyone is different, so the more you go on in life the better grasp you will get on which foods and activities do you good and bad. Maybe keeping a journal for a while on foods can be helpful for linking types of foods to flare ups.
Hope some of this helped!