Oh Wrensong, I absolutely know what you mean where you can almost zone out and are so focussed on your flushing / sweating (both in my case), that you can't process what is being said or is going on around you. I am retired now so don't have to be in too many awkward situations if I don't want to, but towards the end of my working life, I was on the front desk of an estate agents and I can remember the feeling of dread every time someone walked through the door and I wasn't sure if my face was going to glow like a lightbulb! You can feel it coming on and that is all you focus on - it's dreadful.
When I was younger I was never a blusher, I always had pale skin and didn't blush whatever the situation was, but I feel I am certainly making up for that now, but this heat comes from inside and rushes up to your face and takes over your body.