Shirl,
I'm so sorry that your son, and you, are going through all this. It has to be so hard.
I have simple and complex partial seizures. The only time it hurts is when I have a complex partial and do something to injure myself during it, like bump into something really hard or fall on the stairs. The rest of the time no pain is involved. During complex partials no one really knows I'm having one, unless I say or do something goofy. I can look and do things exactly like normal, except I have no memory of it or an altered memory of it. Or, I can say truly outrageous things. If someone doesn't know me they just think I'm nuts. A couple of nights I've come to outside in the pouring rain or the freezing cold, very near the street, with no shoes or coat on. Thank god I had on pajamas. After a CP I'm usually confused for a few minutes, and then I sleep. (except for now, on lamictal, when I can't sleep much at all. Still as exhausted, but can't sleep)
I could imagine someone having a complex partial and hitting the wall or banging their head. Some of the people in here have said that they get violent during partial complex seizures.
Before I have a seizure I sometimes get an aura. For me these are a strange electrical-like feeling plus a feeling of dense forboding. It feels awful, but it isn't painful, either. It can last a few minutes or on and off all day long.
Simple partial seizures - for me they can be smelling something weird, not recognizing where I am or the people I'm with, time and size warping, hallucinations, memory zingers from the past, and a few others. The really hard one is a fear seizure. Fear is an understatement. Someone in here described it as how you'd feel half way down when you jump off a building. But it's just for a few minutes and then I'm just really tired and need to lay down.
About your son's self-harming. Sometimes the meds can do it to you. I really haven't talked about it at all in here, but on the Lamictal I get these intense thoughts and urges to do things that are, well, physically self-destructive. The thought drills into my head and for some time I can't get it out of my head. I've got it well under control, though. I haven't actually done any of it. A few times I've had to walk into another room and remove myself from whatever is included with the urge. The only drug that has done this to me is Lamictal, but I've heard of other drugs doing it to people, too. I think that if this happened to someone without the mental skills and self control to cope, it would get pretty dicey.
I guess the bottom line is don't worry about your son being in pain. He's not. But he may feel confused, scared, or tired. And those things you can help him with.