First off i want to say that i am appaulled by the way the middle school is handling/or really not handling your son.
I would make an appointment with the principal and your son's team of teachers and the special ed director ASAP
This is what we did, when problems arose out of the blue.
Write a letter of your concerns and recent problems and have it sent to them registered mail that would require a signed piece of paper{start the paper trail} that they recieved your request, they then have 5days to set up the meeting from the date of your request.
WE have done this with all 3 of my kids, it sends a message to them that they can not bully you and your child anymore.
There is no-way he should still be getting in trouble after this meeting,{honestly i am appauled that the school has not set up something already, waiting for a dx should not really have such a wait, for benefits to be put in place} things will be set up to help him/the vicious cycle should stop.
OH, AND YOU CAN VERY WELL GO INTO THAT SCHOOL, DO A WALK IN AND REQUEST TO TALK TO THE GUIDANCE COUNCELOR OR ASST PRINCIPAL, MAKE YOURSELF VISABLE TO THEM SO THEY KNOW YOU MEAN BUSINESS ABOUT GETTING YOUR SON HELP. Do not push this under the carpet you pay town taxes/right and their salaries???
I realize that this might sound harsh, but this is how they are treating you and your child, you and your son should not be dealing with this alone. I have used an advocate in the past, they are usually free and/ and its someone else in the room during the meetings that listens to whats being said so that you don not forget all your questions and yada yada yad. You also can call the state board of ed and chat with their autism specialist and see if the school is in direct violation in the state you live in. I have used this for years even after our dx of moderate autism, mild mr, and 3 paragraghs of problems when my son was 3 1/2yrs old, he is almost 20yrs.
They helped me in this way, they told me what to say to the different school principals and how to say or write it , what the law is in the state you live in and what the school is responsible for/for your child. If they are unsettled by what you tell them the problem is they might just call the school themselves and request a meeting, this is the state board of education and there are guidelines and laws as to how they have to act, the schooldistrict you live in could also get fined and not be in the good with the state.
Ps i am thinking autism also, but there are many dx's your son could fall under, the outbursts i know very well
good luck to you, i will follow your story and you can always chat with me, i am here to help you and anyone else with this dx