Sensor problem

mvsfc

Hi! I've a Nikon D3100 and for the past few days I've noticed a white line in almost every photo I take - it's like a white shadow. I don't really know what it is, but today I went to a photography shop and the guy told me it could be a sensor problem. Does anyone know why this is happening?

Here is an example: https://www.flickr.com/photos/115930654@N04/14054657035/

I tried to edit the photo in a way that it wouldn't draw much attention to the line, but in some of my other shoots it's a lot darker.

Thanks

ohyeahar

Do you use a filter (e.g., UV filter)? If so, try shooting without the filter and see if it's the same.
Could it be the lens? Does this happen with every lens you try?
If you switch to live-view, does the white shadow appear on the LCD?