Keyboard add random Period while typing

My MacBook Pro keeps adding a period after certain words while I am typing.

it happens quite often especially when using word doc and sometimes Safari, Facebook, etc.

it probably started doing it back in October. it sucks because I'm writing papers for school and I look up and look like this [This. is an. Example. of. what. my papers. look like.] just add about 3-4 paragraphs