Vagina hurts after masturbation?

You might have been to rough when you were masturbating. You could go soak your vagina in warm soapy water and see if that will take the pain away.

You said it was still packaged? I could be wrong, but I'm assuming that most toothbrush packaging is either the carboard backing with plastic kind, or a sheet of sealed plastic that most likely has a rough edge on it? If that's the case, you might have just scratched the walls of your vagina a bit. It'll heal like any other scratches - don't use soap or anything on it, since you shouldn't do that at all, but maybe rinse the area with hot water in the shower just to clean it up a bit.

If you meant to say you took it out of the package first, my only guess is that you were probably a bit too rough or not lubricated enough and using the toothbrush may have caused too much friction, so the same basic idea. A brand new and therefore clean toothbrush couldn't caue an infection, much less that soon afterwards, so don't worry about that. If it still hurts much later, even just tomorrow when you wake up, maybe ask a doctor just in case. But I doubt it's much to worry about, you were probably just causing too much friction.

you were just too rough and give it time too heal on it's own

nothing bad will happen. it probably hurts because you may have gotten a little aggressive with it, or if you've never put anything else in there. it's generally not a good idea to use anything that's not supposed to go in there, because it may be made with dyes or plastics that aren't "safe" simply because they aren't made to go in there. but everyone (mostly) has done this sort of thing. nothing will happen to you. I'm sure the pain will go down. try taking a bath.

Use the proper toys.