This letter could have been written by me, many times with my DS14. He was always forgetting to bring things home from school so he would not have the workbooks necessary to complete homework. Even when he did bring them home, papers would get "lost" in the backpack, the desk, left at home, dropped on floor, you name it. Any decrease in his grades from A's was mainly due to missing assignments or late work. The only testing we had done for my son was the school's IQ testing to qualify him for the gifted program. He had qualifying scores, but unlike your son did not have processing speed issues. He was as you describe though in a fog, not paying attention; teachers described him as unmotivated and socially young.
Strangely in 8th grade is when things really changed for him. All of a sudden, he was keeping up with his own things and really doing a great job with it. This could be due to classes becoming more challenging or him just reaching the maturity level to keep up with everything.
Some tips I tried when I was really having an issue. Every day, I shook out everything in his backpack. We went through all papers one by one, papers that could stay home and/or be disposed of. Put any papers that needed to go back to school in special folder. He picked out folder it was a certain color and he knew any work that the teacher would call to be turned in was in this folder. One side of folder had completed work and the other side was for work in progress. He also kept a daily agenda where he wrote down all assignments, upcoming tests, etc. I checked that daily and made sure all assignments that were due were in backpack. If they weren't there, he competed them again so he could turn them in. I asked a lot of questions and spent a lot of time going over everything. We also checked for necessary supplies, pens, pencils, paper, colored pencils etc. and restocked anything that was missing.
On second thought, maybe in 8th grade he got tired of me going through all his stuff every day and asking so many questions, he decided to do it himself.
Best of luck to you in getting to the bottom of this.
