You probably don't want to hear this, but it might be time to start looking at ileostomy. It will not cure Crohn's, but eliminate the reservoir that tends to be the issue with folks with Crohn's. You can try a diverting ileostomy and see if that at least puts you in partial remission. Then you sort of will know where your path is.
The fact that practically nothing has been effective is what leads my thoughts in that direction.