Vit C, especially in larger amounts, is a stimulant. A more "natural" one but a stimulant nonetheless. That is why I think taking large amounts of it for a long period of time is probably not a good thing.
Anyway, like any stimulant, when you go cold turkey you experience side effects (think quitting smoking, coffee, etc). Aches and pains go along with all of that. When I stopped my stimulants (did not include Vit C but other things) I had aches and pains too.
I can't say whether or not you have scurvy, but I know you're body is going to have some major adjusting to do if you are stopping the Vit c and think you need to be aware that you could have withdrawal symptoms.