I don't have much to add here, just wanted to share that we have similar issues with DS (turning 7 in a couple of weeks). Punishment never works for him, it just makes the situation much worse and raises his anxiety levels even higher. What we do when he is getting violent is take him to our room (the kids' room is too full of things he can throw and break; they share a room and there are only 2 bedrooms in our house). But he can't be left alone because he will make a mess and try to break stuff, etc so someone has to be there with him. It's a tough dance - he needs to be somewhat physically restrained so he doesn't try to break or wreck stuff, but if we get too close he will hit us kick us etc so we need to keep ourselves safe. I tried the "holding" thing but that made him really freak out. The GFCF diet does seem to be helping reduce the frequency and magnitude of these incidences, but they are still an issue. We just got him an autism diagnosis and are now in the process of building a support team for him (we homeschool, but get funding through a provincial homeschool program). This has made me feel a lot better as we will now have help and new ideas on how to not only deal with this situations but also work to teaching him better coping skills.