Hi Jules,
I hope you don’t mind me replying. I am the youngest sibling of a man who is living through undifferentiated sz and was diagnosed when I was about 6. My brother is 11 years older then me. I usually don’t post here, but I do answer a lot of private messages only because my brother is on this site big time and I don’t want to post anything that is too personal. But I feel that for this one, it will be OK.
( Yes, I checked with him so he won’t be too surprised) 
You’re guy sounds great. I do mean that honestly and with a kind heart. It sounds like he’s working really hard to get a handle on this. BarbieBF is correct, he’s handling this very well. From what your typing it really sounds like he’s working his butt off. The being unresponsive, tired, grumpy sounds just like negative symptom or reactions to the meds. It can take a lot to get that balance just right. It does take a lot of patience.
When I was about 10, my brother disappeared on me for a few months. I was hurt and confused. I love my big brother with all my heart and he is hero to me. But he disappeared. I couldn’t believe he left me. ME! His best friend and side kick. ME?! the partner in all his capers and adventures. When he was found and came around again he told me he was facing a an arch villain so dastardly, so ugly and evil that he just couldn’t risk bringing his side kick into the fight. He didn’t want me hurt. (The dastardly villain was his SZ) Every time he withdrew from our parents and I, he said it was to protect us from the worst of this disease. Just talking to your guy on-line and on the phone is helping him. Letting him know that your still there for him is helping him.
My brother gets very upset with himself when an episode occurs. He’s embarrassed and he doesn’t want me to see him at his worst. When we were younger he would lock himself in the airstream trailer in the back yard and hide from me. I wouldn’t try and force my way in all the time. I would just slip little notes in letting him I’m still thinking about him. Sometimes when he would re-emerge I would WANT to ask a 100 questions like… “how are you feeling? are you taking your meds? what can I do? how do I make this better?”
But that would have just sent him back into himself. He would have withdrawn at all that. But (I know this sounds odd) but sometimes just ignoring the SZ and going out just for a 20 minute sandwich is the very ticket.
It was something he said really helped. He just came off a traumatic episode. Reliving it, explaining it, talking about it right then was just not something he even had the strength to do. So just having a sandwich and talking about a comic book or anything other then the sz made it so next time he was out for 30 minutes, then an hour and then a day and two days…
BarbieBF has mentioned in many of her post that she approaches her son in a calm and level manner and it’s the same with me. I just don’t keep talking about it. (with him) I just hang out with my brother. Because, yes, it was all new to me, I wanted to discuss every detail. But he’s already been living with it for a while and he wanted to feel like there was more to him then SZ.
One thing that I feel put him at ease around me more was I was getting old enough to start learning about the more clinical side of SZ. I was given books to read and talked to by therapist and taught WHY my big brother was doing what he was doing. I didn’t discuss this with him. I didn’t sit down with the book and say, “Well, it says here you also do example a. Interesting.” I would never do that. I can only imagine how mad that would have made him. He already felt like a science experiment due to the detailed conversations he was having with his doctor. He wouldn’t have put up with this from family too.
I discussed stuff with my SZ support group and got ideas on how to reach my brother and how not to get my feelings hurt all the time, and how to just hang out with him and begin to recognize when something is triggering. That really helped me a lot. I wasn’t afraid of him. If I ever got upset over something he did that I didn’t and couldn’t understand… Learning about negative and positive symptom helped me see that he was still working his butt off.
Learning what I can and getting new ideas helps me appreciate everything he does for me.
It’s also built our trust so when he doing well, he will open up more… when he is able.
Sorry for book, like I said, I do answer personal messaging through this site so feel free to ask anything. I hope that you also get some ideas… he sounds like a good guy.