The nutrition/hydration/mental preparedness advice is all excellent, so if you're really hurting, give all of those things a shot. Each person is different, so who knows what will work for you.
Ultimately, though, motion sickness deals with the sensitivity of your vestibular nerve and the fluid filled canals in your inner ear, which send conflicting signals to your brain about your body's movement and orientation (this is all old news since most of us here have been through API). The point that I'm trying to make with that, though, is that like genetics/athletic ability/alcohol tolerance/etc., this sensitivity is different from person to person. The good news is, just like with most everything else, your body adapts fairly rapidly to its new environment. So while all of those other little tricks and methods might ease the transition, adaptation is going to be your biggest friend. Unfortunately, sometimes the road to wellness is not very pleasant, but you'll get there. I was in your shoes before flight school, as well. Airsickness was my number one concern, and I did hack several times, but it passed, just like it does for 99% of the studs in the program.
I know that there are the very, very unlucky few who's systems' are so sensitive that they never adapt, but I wouldn't sweat it. You'd already know if that applied to you, as there'd be no way you could get up into a civilian plane and not feel it. Good luck.
