Hi functioning autistic 9yr old boy with anger issues

Hi,

thank you for taking the time to read my query.

Our 9 year old boy has been diagnosed as highly functioning autism, he does OK at school, attends swimming, diving, rugby, judo, cubs including two day camps and has a steady group of friends. The school contacts us around once or twice a term to inform us he was upset today for what ever reason. He also gets upset with himself when his rushed maths work has mistakes. 

A recent school outing caused him to be upset and teary with the teacher as the group he was in didn't share with him the type of activities which he loves, although he held it together at the trip, he vented his frustration on himself, in front of us at home. Upsetting to see.

We have tried telling him his mind when healthy through exercise and even computer gaming (dealing with losing) can all help toward a healthy mind that can help him cope when he is upset with whatever may be the cause.

Can anyone offer some advice? we have attended the Barnardos six week Autism education course and although very informative covered every aspect of the spectrum and we feel we need pointed in the right direction specific for our boy.

Again, thanks for your time.