Ok... here is my promised long and hopefully helpful response:
On your RMT:I think that you aren't getting the gentle support that is required given your 'awakening' experiences. For your RMT to give you the "riot act" so to speak for not setting up protection during a self-healing is ludicrous in my mind. First and foremost, we should remember that we are human, and we will make mistakes. We will forget things.
A gentle reminder that the way he/she teaches is that you should set up protection under all circumstances when facilitating a Reiki session would have been sufficient. You are obviously a grown adult if you have children, and as such, you shouldn't be treated like a child and yelled at (I wouldn't yell at a child like that either) for something that small.
I'd suggest finding a new RMT. There are several on this board who live in the UK that I'm sure could help you out and give you the gentle support you require.
On Protection:There was a good thread on this board about this very thing.
http://www.reikilearninglounge.com/reiki-general-f1/protection-reiki-t39.htmCheck out that and see what you think. To summarize though:
1) Some people believe they need protection. If you believe you do, then you do. It is that simple. It isn't wrong, its just how you choose to perceive the unseen world.
2) Some people believe that you don't need protection with Reiki, as Reiki provides its own protection. But that you still need protection against other spirits and negative energies. Again, if you believe you need protection, then you do.
3) I personally don't believe there is any such thing as negative or positive energies or entities. Merely energy that is or is not compatible with your energy. If it is not compatible it can bring your energy out of balance. Simple balancing exercises can take care of this. I do not need protection.
You can study and read all the thoughts on this, and decide for yourself what you want, and then live that belief system. Its all good.
On your Experiences:Often the first reaction we have to new experiences, is to be frightened. It seems you were frightened and wigged out a bit by your new 'awakening' experiences. The man who said hello to you, well my impression was that he wasn't being threatening. So next time you see him, say hello back and ask him what you can do for him. The mundanity of the interaction may surprise you.
As for your son, many children tend to be empathic to a certain level with those they love. Especially parents and siblings they are close to. I'm not very familiar with Autism, so I can't speak to whether this would be more prevalent in an autistic child. But I do know that one of the symptoms of certain types of autism, is that the child does not know how to process the sensations they are receiving. They are strong and the child often becomes overwhelmed by the sensations. So it is possible the reason your child is acting frightened, is because he is picking up your fear and exhibiting it without realizing it. So if you work on being calm and collected with your new experiences, your child is likely to follow suite.
If you have any further questions, don't hesitate to ask!