Hand flapping

My son is 10 and he has CAPD and sensory issues. He has been hand flapping since about Jan 2016.

At school it was not problem last year. His case manager was fine with it. He moved to 4th grade and now his new case manager I guess is having an issue with it. It is all I hear about, he is hand flapping, it is distracting him and others.

He has tools at school from the OT to use but he says that they are not working. I keep telling them to get OT back in, his flapping will not stop nor can he control it. I keep telling them it is how he deals with stress, anxiety, over loaded sensory processing, etc.

I don't know what else to tell them or how to make them understand.

Any ideas?