I'm not a doctor, either, but this sounds like a classic case of altitude sickness. The pain may have been due to a blocked eustachian tube, or may have been caused by oxygen shortage.
The symptoms fit well with symptoms reported by "first time" trekkers in high altitude areas, such as Nepal, who have not spent long enough at intermediate stops to acclimatise.
I don't know what "oxysaver" is, but it sounds like a deliberately reduced oxygen supply. If you have to do this type of op again, I'd be inclined to try using a full flow system, oxygen supply permitting.
If it recurs, I'd definitely see a doctor. Not a smoker are you?