what is this? *major TMI warning*

MAJOR TMI!! I am on the depo shot, my first ever shot was on the 18th May 2018 and I got a 12 day light period, very like spotting(between 30th May and 12th june). I was suppose to get my period on the 1st July and it didn't arrive. went to the bathroom this evening and seen this in my pants! wtf is this!? it is very brown in person.