Hope you feel better soon. Don't worry too much - it's been bad in the past, and you've always got past it.
I wouldn't be so quick to write off altitude as a contributing factor - I think the speed of ascent is relevant too - I was definitely feeling altitude sickness symptoms after climbing Ben Nevis which is much lower - but we climbed it fast, and it was a hot day and halfway through a week of M21L. A few days of rest and not worrying about it, you might feel much better.get yourself a good long book and don't do anything else until you finish it. Best of luck!
Thanks for that message, Mark, appreciated.
I'm resting a lot, staying out of the sun/heat, and slowly starting to feel a little more human.