severe lower back pain

i am a mom of a 22 yr old cd son (dx at 16 with very little issues until recently) and this week has been really hard. last week he did a solumedrol iv (he generally does very well with the steriod iv) and his gut flare was gone. a few days later he woke with pain in his lower right back. got a hold of his gi (which isn't easy for some reason) and he had us go to the er. i should say my son is in college and i am 2 hrs away but i insisted on meeting him there. they did 3, yes 3 ct's looking for kidney stones, appendix problems, or what ever they could find i didn't even know they did 3 till after the fact. 1 was w/out contrast, 1 w/ injected contrast and then the 1 w/liquid-swallowed contrast, i didn't know they did the injected one right after they did the w/out contrast, i didn't go back with him of course, anyway gi said that there was no sign of a flare. they gave him an iv of flagyl, and iv of cipro and an iv for liquids. gi says he "thinks" there may be a small abcess started but never did come up with why he is having this pain. well, he woke the next morning with the same pain and additional pain all over. this morning he woke with pain in left and right lower back, gut pain and feels horrible all over. i called the gi (my son is still trying to do all his classes, 4 today) and they are having him come in tomorrow morning. my question is: has anyone had this lower back pain, and if so what does he ask at the gi tomorrow. he knows to make sure there will be no more cat-s but i am trying to still teach him how to get info out of the gi because that is an art in itself. we just need the right questions to ask and i need to make sure he asks. i have told him i have been on this forum and i am hoping he will join soon. he has yet to meet another person that is going thru what he is....he is feeling very alone and oh yea he won't tell any one at college, old friends from h.school knew but .....very stubborn and proud. he has been on 6mp (75mg), pentasa (3000mg) since the beginning and cimzia for about a year. went off meds but cimzia for about 3 to 4 months. (prednisone on and off)
thanks ya all, it is now my place to come and see what's good (? but some can make me smile) and what's bad about this disease, i have learned more here then all the pages i have read on the net.....

I suffered from some serious bad back pain (low) for 6 years, the worst was last 2 years the gp never knew why i was having this pain with some other symptoms until april 2011 i had a severe pain in stomache ended up in hosp... opperated on me and removed 50cms small and large and told me my intestines had perforated from 2 places and they diagnosed with crohns.
After the opperation my back pain is hardly there the pain use to travel into the leg.