The Pain of Childhood

I wore long sleeves today, despite the 80 degree weather. Didn't want anyone at work asking about the fresh scratches on my arm. I mean, they know, but sometimes it's easier not having to explain. The scratches sting a bit under the light fabric of my blouse. At home now, I hold a cool glass of wine against my skin.
Moe is going through another round of aggression. But it's worse this time; he's not just hurting me and Jeff. He's hurting himself too. His forearm is bruised from where he hits it agains the edge of the table. He's been hitting his forehead as well, on the couch, the rug, and—scarier still—against the sliding glass door or the bathroom counter. So far, we've kept him from truly hurting himself.
He goes from aggressive, to sweet and wanting hugs, to insisting on some pretty hard pressure on his head, back to aggressive when I'm not doing it just right. I know he's just frustrated, but it's hard not to take it personally. I'm only human too.
This has been going for on a while now, maybe a month. Jeff took Moe to urgent care a couple weeks ago. There was no ear infection, no strep throat, no other obvious issues. They didn't exactly dismiss us, but did suggest that we work with the doctor who "treats him for his autism." I'm not really sure who that is. But we know this is more than just behavioral. More than just autism.
We worried about headaches. I started to wonder if maybe we needed to get an MRI. Perhaps some tumor (maybe one that has been causing all his delays?) was causing some pain. This is the screwed up life I lead, almost hoping that he would have a tumor, then quickly banishing the thought, guilty for it even crossing my mind. But it would be an explanation as to why all of this is happening to Moe. That's the bargaining stage of grief, I'm told.
We got an answer on Monday, at least we think we did. We took Moe to the dentist guessing that perhaps he had a cavity. It seems he is getting new teeth. I forgot about those "six year molars." It makes sense, the pain that comes and goes, his asking for pressure on his head or near his ears. It helps, knowing the reason why, that this too shall pass. And yet, I feel resentful that something so simple, such a part of normal childhood development, could cause so much havoc on the entire family.
And Moe, poor Moe. The only way to tell us he is hurting is by hurting himself more. I tell him I want to help him. But I don't know how.
It was the best possible outcome: an answer that points to something concrete, but not serious. Still, we are all wrecked, rung out, exhausted. And bracing ourselves for at least several more days or weeks until this tooth is in.
I can't even imagine what is going to happen when he starts losing his baby teeth. It won't be long. Moe turns seven next month.