Ugh, I had and have a lot of this. Now bear in mind, I'm not a doctor. I do however have Hashimoto's thyroiditis, bipolar disorder (NOS), depression, anxiety, and GERD. I recently figured out I have Fibromyalgia too, since my mood is finally "normal" with being on Lamictal, but all the pain is still there. I'm betting your kid doesn't just have one thing, but a few different things occurring together (co morbid).
If the doctors can't help you, you need to start doing your own research. That' the only way I ever figured what was wrong with me. Doctors can be really useless.
You know, the thing about him sitting up at night and coughing, vomiting, actually sounds exactly like what I have. It's GERD, but a different kind. I only recently found this out on this site (!) because I've been waking up unable to breathe and it didn't fit any kind of sleep apnea.
Is he on any meds? I got some of this stuff when I was fist prescribed an anti-depressant at 12. It was an old-school one and was just awful with the side-effects.
I think probably has that, plus either fibro or CFS, and maybe a thyroid disorder. When I'm hyperthyroid my stomach stuff is worse, since it produces more acid. The tingling and pain sounds like Fibro. The temperature regulation problems sounds like a thyroid problem. Like I said, I think some of these go hand-in-hand.
The only one I haven't had is the bladder control problem, I think. The limb jerking was a med side-effect, but if I'm really anxious, that can come out too.
Depending on his age, the bladder thing might just be his reaction to stress. Harder to control that when you're young.
Ugh, I just typed out a super long comment, but lost it. If you want to, after you read this, you can message me and I can give you my phone number or something. I know what this is:
"Day before an episode he will have exaggerated reactions to things."
That and all the pain. It's an overreaction to stimuli. I've been getting that on and off lately. I'm not sure why. But when it happens, my fibro symptoms are out of control so the pain skyrockets and it's all connected with anxiety too. The only thing hat has helped my anxiety and irritability is nicotine. An e-hookah would be your best bet. Fruity flavors. I can't type out as much as I did before, but I'm just trying to help here. I do need to get some sleep soon, but I'll check back when I'm up again.
Oversensitivity to stimuli, I mean, which is why there's the overreaction. Smells, tastes, touch, motion, sound. It's all awful. So strong it hurts. Causes extreme nausea, dizziness, possible vomiting.