Your son requires a very srtuctured predicatable routine and environment.
As far as cleaning up - remove any unnecessary items from his area. Take things out one at a time - and require they be put away before the next thing comes out.
What type of school
placement is your child in? I ask this because, homework needs to be regulated to his tolernace level.
First you want to develop a skill, then through practice you can help him build endurance. Remember, after a long day outside the home his properly pretty wiped out. How much homework does he get? Does he have any down time? You need time to be his mother and he needs nuturing after a full day too. Talk to the school. If all he is doing is school work he has an endless day. No child could handle that.