Honestly I believe that the artist was lying when he said the song was about advil to get people to stop asking him about it and to help him forget.

If you try to interpret the song being about sickness, one or two words never mind whole verses could be taken that way. Its just way too little. Especially whenever 90% of the song is referring to a person. Can advil walk away?

Just saying the artist doesn't always want to tell the audience exactly what the story behind the song is. Events that bring so much emotion aren't always things that we want to talk about, their very personal, so
to stop the flood of people from constantly asking him about it, he deflected the questions before they came by saying "It doesn't really mean anything, I was sick when I wrote it".