My DS seems to have a mind of its own... (I fixed it)

Lately I've noticed that my DS starts to do random things, like the touch screen is possessed or something.
For example, when I play Super Princess Peach and do some vibe that isn't crying, she starts crying instead of doing the vibe I wanted her to do.Edit: I can't calibrate it. I think it broke :(Edit edit: Plastic.

it's broken, but that part is easily replaceable,
if you're from around my town we can fix it for some 12 dollars.-edit. oh there was a plastic? lol