Hi, Can't Stop Crying! Here's a perspective that may or may not be applicable or useful for you:

Right now, managing your son's illness comes first. His longer term educational requirements need to adjust to him, not the other way around. School may certainly be part of his healing, but school is the servant here and cannot be the master given the severity of his condition.

Can he still do enjoyable things? How complete is his disinterest in life? Has he had a full medical workup?