Got dirt on your sensor, go on and brush it off with this full frame sensor swab. Make sure you use the right fluid, I used the wrong fluid once and it made it worse. Sorry Dad, I fixed your sensor eventually.
Here is Visible Dust's wet cleaning guide: https://www.visibledust.com/technology.php?art=wet_chat
But if you don't want to clean your sensor yourself bring it in to us and for $45 we'll do it overnight, and $65 while you wait!