blood chunk

Has anyone ever felt a gush and have it be blood? I felt a small gush and I cleaned myself it was blood and then I went to the restroom and a big blood clot came out. But after that the bleeding stoped. Then came back later in the night light pink. I called the Er and they said to go in if contractions followed.. just wondering if it's happened to anyone else. And what was it that was going on I'm currently 36 weeks