I volunteered at a therapeutic riding center. Over the years we had many riders with autism. Their parents said it helped a lot. Ours was free to kids. Maybe you could see if there is one within driving distance to you.

The kids really made a connection to the horses and loved coming. We often had a parent side walk with the kids to help with communication.
Riding is also good for them because it mimics the natural walking process to the riders muscles and we saw definite improvement in their walking skills.

I am so fortunate that none of my kids has a disability like autism-I saw and heard what the parents went through and still are. My heart goes out to you.