Wow I'm so sorry the first thing we need to do is figure out how to get him some sleep so yours isn't so broken, you need some rest. I've been there done that feeling your way along the walls to coffee, people who ask "how are you?" are met with tears. If haven't already might ask prescribing doctor if it would be ok to give him some Melatonin till he gets use to the new dosage. 15yo's developmental pediatrician had her taking that until we started the seroquel because poor kid never slept more then 4 hours in her life. Regular pediatrician said give her a little benedryl when she was 2yo and it acted like rocket fuel (so did exact opposite) think they called it paradox reaction or something close to that.
Hope they can figure a way to get him some sleep soon as sleep has a lot to do with the whole stability issue. He's only 11 yo and it looks like there is bipolar in family with-sister (full sibs?) I wouldn't carve it in stone that he doesn't have a mood disorder at this point. Though having 2 bipolar kids I tend to see bipolar everywhere. Hoping you all get some rest soon.