If you have an IEP and the school cannot provide what he needs, you can request that they pay for a school that can give those provisions. You need to check your state laws. I think that here where I live, you need to give them advanced notice in writing (a certain number of days before switching schools). If they do not agree and they can't provide what he needs, you can go to mediation or due process. You would need to prove that they actually can't provide the services, and that the other school really can.
where I used to live my 8 needed a more supportive classroom and no one in the district would help me I even made an appointment with the special education department and all they could say was lets just observe and see how he does. When we moved to where I live now the school district tested him and he is on a pre k level in the second grade. They had to put him in life skills to get to a kindergarten level by the end of the year. But before we moved here I had to go the extra mile and find him a school that would be able to help him.
My experience has been going from the mainstream setting to the contained EBD setting before a different school setting/placement is ever considered. When that setting could no longer "educate" kt or wm, it was recommended that they attend day treatment - no arguments here. (Day treatment came after hospitalizations then Residential Treatment Center (RTC) settings though).
I can't remember what setting difficult child is currently in right now.