When the school bus brakes screeched in his ears, he punched a hole in his seat the size of a grapefruit. It could be crossed sensory circuits making Max cross. Use sensory tools for calming and increasing his productivity and self-esteem. This means, however, trying a thing or two that would have driven old Mrs. Siddupstrait to early retirement or you to the corner to write 100 times you'd never do it again. If Max's senses can't receive, modulate, integrate and organize input, he lands on the floor, then goes through the roof.
Sensory integration benefits all children.
And even adults. No one is too old for it. It tells you exactly what they need. You get an edge with kids Max's age. Then, tell them they aren't clumsy, bad, dumb or lazy, and that they are not alone.