Does this sound like regular decidual cast or otherwise?

I took plan b and did not have my period. I missed an entire cycle. I’ve had negative test after negative test. Finally I have my period on day 29 of lateness and I pass what I believe is a decidual cast. It is a large bit of flesh and tissue but does not resemble a miscarriage. This is the third time I’ve had this happen but a part of me is nervous that I have ectopic pregnancy that is not showing up on tests. Is there a way to rule out this worry? Is this normal for plan b and missing a period? I also was severely sick and have been throwing up unable to keep water down for 12 hours then I was able to eat crackers and finally a dinner. Im still throwing up today after passing the tissue. My heart was racing from 120-140bpm all night the night before I was throwing up and I had shaking. I just want to make sure it is just a decidual cast. Should I head to a doctor?