I have the same problem with my ribs. Mainly my left side and it feels almost puffy. I have no idea what organ is there. I have had this pain off and on for months, mostly on. Seems worse when I am sitting sometimes it stops when I stand up and then it will kind of twinge with pain. Almost like a spasm or something. I have no idea what it is. It's hurting right now.
If you find out what it is, let me know and I will do the same for you.
I sometimes feel like I have pains going down my sides and down the middle of my back. I don't know if it is bone or muscle. It almost feels like muscles, but it aches like bone.
I didn't know if the back pain was Crohn's related or not. I got crappy genes both ways. Crohn's on one side RA on the other.