He's a grown man; surely he doesn't expect you to look exactly like you did when you were a kid, unless he's as dumb as a rock. Still, I think you should judge for yourself if compared to other women your age, are you pretty much equivalent to the level of attractiveness you were in high school. If the answer is yes, I wouldn't stress out too much. Not all men expect women to never get older, and the ones who do - in my experience - have issues with their own aging process.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?