You were weaning him off Prozac slowly weren't you?  Maybe you slipped below a tveraputic dose a few days before you stopped.  As someone with experience in depression though he does sound depressed so maybe put the SSRI back in - I prefer citalopram though.
Yes we were.  The higher dose caused panic attacks and he was missing a lot of school.  He has been much better on the lower dose until recently.  
Our goal is to try another SSRI.  I understand that some SSRIs work better for people than other.  Fingers crossed here.