Passed a Grey-ish, Tissue Like Mass While On Period

I have just returned from the Emergency Room at the worst hospital on the face of the Earth. Here is my background and my questions: I have been using the Nuva Ring for the last 2 months. Last week was the week I was suppose to take it out and I did. My period started on Thursday and it was normal. Some cramping and a backache but that is normal for me. On Sunday, I was in a bit more pain than usual when I woke up and started my normal remedy of heating pads and Aleve. Nothing alleviated the pain. At around 3 pm is got progressively worse. So bad I was in the bathroom on the toilet screaming and shaking and could barely keep myself from passing out, the pain was excruciating and not normal. I decided to go to the Emergency Room and after triage and being poked I was asked to give a urine sample, when I went into the restroom and pulled my tampon out, a few seconds later I hear something hit the water, I assumed it was a blood clot as I am used to those. Big massive, red blood clots. This was grey and looked like tissue. It sort of reminded me of liver. I regrettably did not pick it up and examine it myself but I had the doctor and nurses look at it. These idiots didn't know what it was and flushed the toilet. They were assuming I had a miscarriage and took my blood. Is that what that was? It did not look like a sac by any means. When I got the results I was told, I was not pregnant, I am anemic, my potassium is low and my white blood cells are elevated. But because the only symptom I had was vaginal pain and I felt better after passing the mass.... I was sent home with no further action. I was instructed to see my gynecologist which I will as soon as I can come up with the fee. But I need answers NOW! I am worried, I am terrified and I can't get that grey matter out of my head! Someone help me, Please!!