Couple of things... your new helmet just might not fit properly, you're not used to it, or it might just be too heavy...
I got one of thos e\Italian flip up helmets with the built in eveshades.. took off for the west coast... did not realize how heavy it was until I was halfway there... my neck would be numb everyday after just a couple hours riding... It is just a heavy helmet...(Used once, now for sale!) <G>
Ended up buying a new helmet on the last trip becuase the Shoei that I really like, and wore BECAUSE I could fit a baclavia under it, was just loose enuf that the wind kept trying to rip it off my head.
I ended up with and extra small ...oops!... Harley full face, but it fits well...
mary