What exactly is decidual bleeding?!

I had an oops (failed condom) on the day I ovulated!. I am not sure if I conceived, but about ten days after that I had about three days of light spotting!. I have had that before with my two other pregnancies which turned out to be implant bleeding!. I went to the doctor the fourth day and had a negative blood test and the fifth day, I had weird cramping that caused my bottom to go numb and bleeding with passage of meaty like ribbons of tissue!. I have never had that happen before!. I am not sure if that was decidual bleeding or not, but it lasted for four days and then abruptly stopped!. That was two weeks ago and I still have had negative pregnancy tests!. I have a gut feeling I am pregnant, but obviously have no proof!. Does anyone have any thoughts!?!?Www@Answer-Health@Com

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