Following Happy Chef's tangent, Mk: if you get a diagnosis for the 4-year-old, or maybe even if you don't, you might consider having the 2-year-old evaluated as well. Not wanting other people within 10 feet is pretty extreme.
It sounds like you are working darned hard as a parent trying to keep things together for your kids, and if there's something diagnosable going on it is so much easier to know at age 2 than at age 5 or 7, because that way you can get more early intervention help that makes it easier over the long haul.
Hang in there.
DeeDee
ETA: passing along one of the nicest things someone said to me at a dark hour: "Therapy works." It's true.
The issue with kids being around DS2 is a fairly new thing (last 3 months or so) ... It started around the time when his brain kicked in at high gear and he started doing all his crazy non-2 year old things. His Developmental therapist came along with us to a kids playroom / cafe we go to where his problem with kids seems to be most obvious and as we watched him, we both agreed that it's most likely because having these kids around is too much of a distraction for him. They interrupt his line of thought! lol ... He's usually very much into what he's doing (be it a puzzle, some toy, etc.), really focused on it and if they get near him, he turns into this "mad professor". He's still lacking in speech so isn't able to tell the kids to leave him alone and that's why he's probably more aggressive right now.
