What Does A Miscarriage Feel Like? I Am Not Sure

What does a miscarriage feel like? I am not sure if i had one yesterday. I started bleeding friday but only a little after very bad cramps in my upper tummy. But all the pregnancy tests tested negative. But yesterday (saturday) i got really bad cramps in my lower tummy and back. And then the bleeding was still there and when i went to the toilet there came something out looking like a blood clot but was like a bag and had blood and white stuff in. The bleeding didnt stop and this morning i got little cramps again and again yhere came out something like last night. What could it be. I have photos but cant send them. I asked someone and they said it looked as if i was pregnant