Hello David,
I am so glad you posted this. I never seem to have any physical symptoms either, or at least don't think I do. Sometimes, I wonder that if the mental overload, as you called it, is so consuming, I am not even aware of any physical symptoms. It's the racing mind and not being able to concentrate and just basic flooding of nutty thoughts that is so vexing. That is what I experience when I am feeling terror of a panic attack coming on. When an attack actually hits, (they rarely hit, though I think living in fear of them is worse) I get a bit of tunnel vision and short of breath. When it's over, I get an all over feeling of warmth and bizarrely enough, a sensation that feels good. Maybe it's just the adrenaline leaving my system or calming down that feels to good compared to the all out war with my body it was having 5 minutes prior. Sorry for the ramble. Just happy that you shared. ;)