Hi Ladybuggy. Like Mom23angels stated, therapy is a great idea. If you could get some in ABA that would be ideal.
When I read your post, it made me think of my non-autistic son. He started having severe seperation anxiety the summer he turned 8. I could relate to everything you said, he couldn't be in a room alone, he couldn't even be in the bathroom alone. It turned out that he is bipolar. Now that we have him on a mood stabilzier he is doing very well. He can even stay home alone for an hour or so.
I mention this because it is possible to have other issues along with autism and a large stress can trigger such things such as bipolar.