I got food poisoning and ended up going to the ER last night because I lost control of my upper body. Apparently hyperventilation (while puking my guts out) can reduce the amount of CO2 in your blood stream, making your blood mildly acidic. Before I went to the hospital I was laid out on the ground, unable to control my arms which were partially bent with my hands balled into tight painful fists. Thought I was dying.
So, pro tip, if you’re ever hyperventilating and your upper body gets tingly and starts to cramp up, try your hardest to regulate your breath.
They are right, breathing back into the back increases the CO2 you breath in (the same you just breathed out so around 4% instead of nearly 0% in the normal air. And reduces the effect of the hyperventilation.