I think I have recently had high altitude sickness. We ascended to Kangding in China where we were sleeping at an altitude of 2700m for five nights. Over the first couple of days I had a slight headache only when we went on a walk during a day trip which took us to 3700m. But on the 4th night I felt nauseous and had a racing heart. The nausea quickly subsided over night, but the next day the racing heart was more severe and I had horrible chest tightness. I went to the local hospital where they put me on oxygen for 2 hours. And we decided to shorten our trip, so returning to normal sea level heights yesterday. I am resting still today and the tightness of chest has subsided. I still have some palpitations and I feel weak and a bit dizzy. However, this could be also due to the stress as I often get palpitations and dizziness with anxiety anyway. Anyway we are due to fly back to the UK on Saturday/Sunday. Is it risky to fly only a few days after having had these symptoms? We will have on 2.5 hour flight to Hong Kong, followed by a 13 hour flight to the UK following that. Thanks for your help.