Can't click on anything within default Mac applications
I'm having an issue where with most default applications (Such as iMovie, Preview, Quicktime, Mail, even Mac Appstore, etc.) I can't click on anything within them. I can hover my mouse over the "x" button and it shows up, but I can't click it. I also can't click on anything on the menu bar when it's focused on the application, so I have to click on another application to be able to force quit it. It gets very annoying fast, especially when I can't even check my email. I can still use any other applications that I downloaded perfectly fine. (My mouse works and everything, but it may have started when I turned off and on my monitor, not sure how though.)
I'm using El Capitan 10.11. Any advice?