Hi Lisa,
I’m so sorry to hear your son is having so much pain, I am hoping the steroids will bring him alot of relief as it did for me (considerable swelling reduction within a week of taking steroids). It is very positive to hear that his sight is returning to normal and that they managed to remove the entire AVM.
I am 3 months post embo (+ small stroke during the embo) and I’m still recovering, it’s definently a patience process. However, I have noticed much progress each week and certainly alot of progress from a few days post op (with pics to prove it: My sight development (post embo occipital AVM)). The focus is that your son is going through a temporary struggle and he will get better 
I am glad your boy has managed to have pain under control to be able to get some sleep. If he hasn’t got them already, some earplugs and eye mask might help with being able to rest too. Hope your sons pain reduces very soon and that he can get to recovering back home soon too!
Very best wishes and love,
Corrine