Re: voice change
I'd be willing to bet that it's a spinoff from your anxiety.
You get slightly out of breath (which is normal) => this makes you anxious about hyperventilating so you become even more out of breath along with the other symptoms => you are now tired and breathing fast and your voice comes out sounding different because you aren't using the usual air stream, but now you've picked up on it and your mind has latched onto it so you are AWARE of it. And when our anxiety is aware of something, we are anxious about it and it gets even worse.
I had a period of time where I thought I was losing my voice. I think I had a hoarse voice some morning and for some reason just decided this was the end. I spent an entire vacation (!!) nearly unable to speak, because I thought my voice sounded odd and that my family would notice and then they'd freak out, so I'd freak out even more...
8 years later and I can still speak just fine. It passed pretty quickly (thankfully) but yeah, all anxiety. Our minds are incredibly powerful.
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