It seems to me that everybody's spine sticks out some. I'd look into it, but I'd look into your posture and see if different positions feel different. You can only fix it if there's something irregular there, and that would take surgery. If it's posture, yes, you can fix that with some work, and it'll save you a lot of wear and tear down the road, as I can attest to. Frankly, plastic and wooden chairs are uncomfortable for a lot of people, though young people usually don't notice it much.