It would appear to me from your description that you developed pulmonary oedema. Also known as altitude sickness. Which will worsen unless you descend. It has all the symptoms of flu or pneumonia. It is not a condition that a Doctor would necessarily recognise. Unless specificly trained in high altitude medicine.
One classic mistake that many people make is thinking that partial oxygen pressure is a function only of altitude. They think that the amount of oxygen at point A is the same at 9000ft as at point B. They fail to allow for variations due to changes in pressure caused by high and low pressure fronts. So the P.O.P at 9500ft at A might be the same as at 10,000ft at B.

The British Mountain Council has some of the best experts in the subject. Who have studied the condition, which affects some thing like one in three people at those altitudes, over a large number of years. They are becoming very worried about Tour Groups who go up mountains without proper acclimatisation. Current recommendation (I believe)is a maximum of 500ft per day over 10,000ft.

One word of warning: Once you develope the condition you become far more vunerable to repeat attacks. So exercise caution.