Pulmonary Hypertension

I was just diagnosed with Pulmonary Hypertension, even though I had a heart cath done in December, my Pulmonary Hypertension is induced by exercise. The doctor didn't want me to start medication in December he wanted me to exercise to strengthen my heart muscle, but I still had sypmtons, I have had several bad attacks of it since December and I worry about his. I will start drug therapy tomorrow by using the drug Revatio. I am also flying on Tuesday and have read this isn't good for people who have PAH. Why is this? I do have scleroderma, and this goes hand and hand with CREST in women who have scleroderma. I am just so afraid of this new diagnoses. What else can I do, and what can happen to people who fly?