SPL-101, don't be too worried about this. You're only concerned about this because it's all a bit of an 'unknown'. You don't really understand the technicalities behind stalling and spinning, nor do you know how you'll feel during such exercises. It's natural that you may feel a bit apprehensive (and excited).
Just do sufficient pre-flight study for all of your lessons, and ask your instructor relevant questions before the flight, during the brief.
Sickness doesn't affect too many people - and if it does it tends to go away after a few flights.
Remember: Knowledge dispels Fear.