help?!

Rina
So I've gotten my period the second to last week of January and ended the same week. So a week has gone by and now I'm spotting with really bad cramps && when I use the restroom it's like really dark blood(like dark brown?) that comes out with my pee.. and when I wipe. 
Any one experience this before? I'm not sure what's happening. 
I also have an implant, but this hasn't ever happened since I've had it in.