What is this? (TMI)

Lily-Anne
I'm sorry for posting a picture as I know many don't like seeing pictures of this type of stuff, but can somebody please help me?
I found this when I wiped, and I'm currently on my third withdrawal bleed since starting the pill. 
This isn't a clot, as I've had many of them before. This had grey hard parts that aren't obvious on the picture, and was solid in a way. When I pushed on one of the string like parts it didn't snap unless I put a lot of pressure into it. 
What could this be? 
Thank you.