when someone feels lousy suddenly, normally low lood pressure and now suddenly hig, dizziness and a bit nausious and mild chestpain . male is a almost every other day in plane travelling with a minum of 7 hours and a maximum of 17 hours. no swollen - red painful leg - so I do not think it is DVT what direction should we think ?
Hello!  After evaluating your symptoms & the discussion I think your problem is, although not serious, what is known as High Altitude Illness.  It has been a fact that a person who has had an acute altitude illness previously tends to be at greater risk of developing acute altitude illness than a person who has previously ascended to altitude or having regular plane traveling, but without ill effect. So, you need not be worried much as these symptoms can very well be controlled with appropriate preventive measures. For example the severity can be minimized by prophylactic acetazolamide. Thanks & take care of yourselves!