Well, yes... I do have this prob too...

But the last thing I would say is raise your handlebars, Meg... that of course depending on what your riding goals are.

For me, raising my bars is not an option, in a race situation that would increase my "wind-frontage" which would mean I work harder because of increased wind resistance.
So what I do while I am riding is stretch my beck/head from side to side occasionally when racing - if i notice it.

When training, I sit up occasionally and twist one shoulder back (keeping hold of bars with other hand of course) and do neck stretches as well when I notice.
And I or my partner rub arnica crwam or oil into my neck muscles at the end of the day. (And I do stretches like Michele describes).