I used to do 2-4-6 days of puddle smoking followed by a couple days of sleep.
I get the jerking around and twitching. I did the same thing. Seemed to do with the insane meth dreams I was having and the drugs aftereffects.
The breathing thing is far more concerning. Are the shards pretty clean? Almost sounds like your lungs are having a bad reaction to the ice, but it doesn't really show itself until you lose consciousness. It's concerning. A allergic reaction maybe?
Obviously meth is generally pretty awful for your lungs, but this is not typical.
If you want to keep smoking that shit, which I would fully understand, I might try a different source. See if a different product that was perhaps cooked somewhat differently might knock out the breathing issue. Maybe, maybe, it's a bad reaction to something in the meth you're smoking now.
If you try a few different sources and it's still happening, I'd say knock that shit off. At least the marathons.
Take it from a longtime opiate addict... Struggling to breathe, not breathing is NOT a OK thing.
I guess you could perhaps just be panicking in your sleep. IOW's, you're having a horrendous meth dream, your mind's still kinda awake/alert and you're panicking. Do you ever remember your dreams? Do you have these kinds of dreams?
I used to have ones where I was in some horrible argument with someone and I'd wake myself by screaming out. Or I was being chased, attacked, and I'd wake myself because I was thrashing around, fighting.
I suppose something like that could cause panicked breathing.
How often during your sleep are you having these spells? Is it a ongoing thing during sleep or just occasional?
