My macbook keeps crashing but says nothing is wrong when I run diagnostic tests.

I have a 13" Macbook Pro (mid 2012) with the most recent OSX. I've been having issues with it since the beginning of March and it happened so suddenly. It would suddenly freeze and the screen gets weird. I have no idea what's going on. Below is the picture of what the screen looks like. I don't know why it's upside-down O_O.

Please HELP! thank you!! 😀