My ds10 was finally granted a 504 meeting this year after a horrible struggle all through 4th grade. We didnt get a diagnosis until midway through the year and at that time I had no idea what PANDAS really was and we had classroom management problems in addition to the teacher being a screamer. Absolute nightmare of a year! Anyway, I thought ds would calm down over summer but we got worse, so at my last visit to ped neuro, I got a letter from them to the school stating that he had PANDAS with OCD. The letteer stating some of the symptoms we were experiencing and how they affected his abilities in class and with homework. That is when they granted us a 504 meeting. I cried tears of gratitude. I felt like they thought I was making it up last year. Even though the teacher witnessed the tics, mood swings, bad handwriting, lack of focus, drop in grades ect. I practically lived at the school last year because I knew this wasn't right. My son had always been a/b and mid year was c/d/and even f's. Not acceptable! Yet they wouldn't listen to my pleas and just kept telling me he didn't qualify for testing. Ugh.....I was beyond livid. To sum up, with your letter from neuro that should be good. That is what finally got them to listen and accomodate my ds.
I wish you all the best this year.
PS, also we were new at the school last year. We didn't have the benefit of them knowing our family. The fact that you know the principal is awesome. Good luck with it all.