Clots at 4 weeks PP

Last night I had pains in my stomach that were very consistent so I took some meds and went to bed. This morning I wake up to feed my LO and passed a huge clot. Within an hour I had passed 4 more big clots that were about the size of a half dollar or bigger. I contacted my OB and was told it could possibly be my period and this could last for another two weeks. He didn't seem worried at all...anyone else have something similar for their first period?