So many people have had the same problem. For me, training in Southern Spain I found the heat made it worse. The other factor which exacerbated the situation was anxiety. I was so worried and pressured that I had to complete the course in a set number of hours I was reduced to a gibbering wreck. The days when I was confident I knew what I was doing were the days when I didn't feel sick. So sit back and enjoy it.
It still took me about 70 hours before I didn't usually feel sick in the plane. Desensitization helps.
You're not allowed to take many medicines when flying, but what you can take (and I swear by) is ginger. Whichever form takes your fancy. I took along a bag of crystalized ginger on every flight. Very tasty!