Hi! I just popped in here and I hope that you are not feeling attacked. It is HARD sometimes when we are passionate about something. The passion we feel can come across as an attack when really all we want to do is share some info.
I am a strange homeschooling mom. My two oldest kids have each spent some time being homeschooled. For different reasons, but we always evaluate the plans every year. Jess is homeschooled now because health reasons and because she was hit by a car on her walk to the bus stop last year (when we tried sending her to school again.) We are trying a virtual high school program for her this year.
The reason for the push for a diagnosis is because it can open up FEDERAL protections for your difficult child and because there is a big push for autism spectrum disorder programs and your child might benefit from them. Also, the treatment for high functioning autism &/or Aspergers is VERY different from treatment for bipolar or mood disorders, ADHD, seizures, etc. We just want you to be aware of the different options.
With any advice on any subject, take what will help and ignore the rest. No one's feelings will get hurt.
As for the over stimulation, I found several things that helped. One was to keep a HEAVY box in the car. Fill it with books that "might" be helpful while homeschooling. Ask him to get the box and bring it inside. Then have him move it to a picnic table, then to the trunk, and so on and so forth. Carrying the weight may help him calm down.
Has he been evaluated by an Occupational Therapist (OT) for Sensory Integration Disorder (SID)? With the problems you describe it seems highly likely he has some degree of Sensory Integration Disorder. Given that, get a copy of The Out of Sync Child Has Fun" by Kranowitz. It is packed with ideas that will help him, are fun and include others, and can be planned so you have the stuff if it looks like he needs to change activities or calm down.
One of the BIG things we did with Wiz, that my parents HATED and my husband even HATED was to keep ALL violent things away from him for many years. If he read about or saw violence, or played cops and robbers, knights, whatever, he went into angry scary mode. He just couldn't keep it together. We took away pokemon, most videos, almost ALL regular tv, we didn't even get a newspaper because he could read it shortly after he turned 3. Even DISNEY movies had to be super carefully screened. If you look at them with an eye to seeing violence the Disney animated movies are SCARY! Remember the scene in Lion King where simba and Nala have been chased into the Elephant Graveyard by the hyenas? The hyenas stop and look back and tell them not to come back or "we'll KILL you!" Guess what my difficult child took to telling us? It was vastly different than what my pcs got from the same movie. The kids watched videos. Period. And it really made a difference.
These are just suggestions. If they don't help, I won't be offended. Heck, MWM and I have sons with similar diagnosis's. Her son has Pervasive Developmental Disorder (PDD)-not otherwise specified while mine has Aspergers. Both are autistic spectrum disorders. Her son is not on any medications to help with his issues. He is best served with other things. My son is on 3 prescription medications - strattera for ADHD, luvox for depression and trazodone for sleep. Each child is different, and we know this.
One thing that I think DOES apply for all of our kids is that we NEED to assemble a Parent Report. It is sort of an "Instruction Manual" for our difficult children. Some parents here developed an outline to help present all the info we have learned about our kids to the docs, teachers, tdocs, etc.... It helps them see what has been done, when, and what the result is. I don't give all of the report to everyone. I esp keep school unaware of some things. They have no need of his latest blood tests, everything the therapists tell you, etc... OFTEN this info can be used against you by people trying to refuse services adn help to you. It IS important to have a master copy that YOU keep and a few xerox copies to give to the "experts".
Here is a link to the Parent Report:
http://www.conductdisorders.com/forum/showthread.php?t=10
Sending gentle hugs to all of your family!