It's hard to know without seeing a minimal example.
For the error you describing my first guess will be to look at the (character and the Rock) if they are on different layers that have different parallaxes. If they are then you need to make sure that all the objects that need to interact with the player have the same parallax, otherwise, there will be an offset between them.
Other than that, not sure what could be the issue.
Have you checked the collision box? and the Origin point if they are set properly? Maybe you cut the picture and the image point wasn't centred after.
If it is none of the above, please post a minimal example showing the issue so someone can have a look at it and give you better help.