This explains a lot! Post Malone was hanging out with Zak Bagans from "Ghost Adventures" and they were viewing something known as "the world's most haunted object. Seems legit, right?
Bagans told TMZ that this happened in June at his Haunted Museum. The object in question is called the dybbuk box which in yiddish means "malicious spirit."
In the video below we can see that Zak decided to take the protective covering off the box and ended up touching it. Post then touched Zak's shoulder then got freaked out and left.
Apparently, this is enough to trigger a curse, which would explain Post's string of bad luck he's been having!