What do I do now?

My
son Marshall,  is almost 6 years old. He has recently begun seeing a child psychologist, for what I suspected was an anxiety disorder.  She asked me to seek out an evaluation due to a suspicion of a sensory processing disorder.  I'm trying to find someone qualified in my area and it is a real challenge.  I'm reading everything I can find online and I am dumbfounded.  He displays so many symptoms that are on all the checklists. I was quite astounded about how
many of his "quirks" were listed.....like the inability to notice
smells, or the noticing of every sound in the background, obsessions
with soft fabrics, always shaking a body part, head, or rocking,
talking to himself constantly. He wont touch anything sticky, eat anything mushy, shoes
cant be snug, etc.

In his fourth year, he started to have difficulty in large groups, at
birthday parties, or museums, often becoming so overwhelmed, that we
would have to leave. I had thought this was a developmental quirk, as
it was new.  This has continued, but until year 4, never happened.  He
used to love stimulating environments.  Thats the part that is odd......until he hit 4, I didnt see a problem?

 This past September, he started school and I was called into the school in December with a
threat of "kicking him out" due to his constant behavioral issues, disruptive behavior
and respect problems.  I was absolutely floored......up until this
point I had no idea there was a problem.  He has never been a "problem child"
and his behavior at home and in other small environments is
fantastic.  He suffered in silence for 3 months until I was notified
and I quickly knew there was a problem.  Being an inner-city school
they had stereo-typed as a kid with a bad attitude from a bad home. 
Once they met with me, they realized this was not accurate.  They were
at a loss as to why he was not adapting.

Upon talking to my son, he was able to describe that the constant noise and
movement in the group of 25 children was too much for him.  He was
acting up, because he wanted to leave the room and didn't know how to
cope.  He is suffering from anxiety issues, a feeling that he is bad
and cant do what is asked. He has started with some regressive
behaviors, clinging and self-soothing in the form of chewing through
clothing. He complains of stomach pains, trouble breathing and what seems like tunnel vision. Needless to say, it has escalated and the school has been
little help.  Since he is learning at grade levels, or above, they will
not evaluate him. 

The teachers, his doctor as well as the psychologist do not feel he suffers from ADHD and he is learning at
above grade levels.  However, he has challenges following directions in
a group, completing work, or completing assignments correctly.  He has
difficulty with transitions as well and settling down.  He has recently
began to be an advocate for himself and is asking to "sit out" in
activities he knows will trigger him, such as group activities in the gym.

My breaking
point was when my son had a particularly bad day at school. 
He had kicked a child and spurted racist remarks (he has never been
prone to violence, or cruelty).  I asked what was
wrong.  He said "Mom, I dont want to be bad.....something is wrong with
me".  Then he broke down in tears.  I just need to have him diagnosed. 
We need some plan of action and some tools to help him cope and
succeed.  He is a great kid and as a Mom, I know something is very
wrong.

I'm sorry for the length of this letter!  If you have any advice for finding a proper diagnosis, or any tips that I can use in dealing with his school, or helping him to cope, I would really, really appreciate any advice.

Thank you so much,

Neysa