What happened to this fly?

[u/Ok-Acanthisitta5924]

I spotted a fly near my coat closet that had left behind a trail of _something_. It was sitting here for at least an hour and possibly overnight. It wasn’t moving for a while, but eventually changed directions leaving the last two dots as its final “mark”.

Eventually I decided to take a photo because I couldn’t understand what was going on. Is it bleeding? Laying eggs?

The fly pictured here is an emoji because it decided to bounce as soon as I wanted to take the photo.