Autism and false allegations of sexual abuse?

My 9 yr old autistic son has recently started acting out "sexually" at school, refusing to ride the bus home in the evenings, hitting himself, and refusing to do his school work. He's mostly non-verbal, but parrots things he's heard. Last week, he supposedly stood up in the middle of class and shouted, "I want to f___ you!" He fought his teachers and the bus driver, urinated on himself, and screamed on the bus all the way home-and two minutes after getting home, he was fine. He's been doing this for a week now. He acts like it kills him to get on the school bus in the evening, but when he gets home, he's perfectly happy. This is really unusual for him, obviously.

Well, long story short, his school called Social Services, implying that he was being sexually abused at home! I'm having him evaluated by a doctor and a psychologist to prove that he isn't being abused. I suspect that his verbal outburst is in imitation of something he saw online (or a complete misunderstanding-last year, his teacher thought he was saying, "Greg likes boobies," and he was really saying, "Great live movies!"). I'm now keeping a journal of his behavior, asking for written records of his behavior at school and on the bus, and taking him to a doctor and psychologist to prove he isn't being molested. Anything else I should be doing?