Have I miscarried? Please help! (Sensitive photo)

PLEASE EXCUSE THE GRAPHIC PHOTO! I returned home after a long-haul flight and had experienced mild cramping and feeling general 'stuff' happening down there. I had some mild nausea, and just generally didn't feel great. I arrived home, was utterly exhausted and slept most of the day. During the day I got up for a pee and noticed what looked like grey / brown tissue in the toilet bowl - like grey looking flesh with one end that looked a bit bloody - that must've come from my vagina. It's now two days later and I feel fine: my breasts aren't tender anymore and generally I feel physically pretty normal. This is my first pregnancy and I just don't know what to do.