A question about heavy bleeding and blood clots during a menstural cycle?

Patient: Hi! I am a 28 yr old female with 3 kiddos and have a question about menstural cycles. Thursday night I started my monthly period and noticed it was heavier than usual. Then Friday came and it was still pretty heavy and I started to pass blood clots. I tried to go grocery shopping and started to feel dizzy and sick, so I had to hurry home. Every time I would use the bathroom, I would pass a clot. And, these weren’t small, they were like the size of a half dollar. By the end of friday night I had passed 15 clots. My husbnad wanted me to go into the ER, but I wanted to wait till the next day (Sat). So, saturday came and the clots stopped but the heavy bleeding still happened. And now today is sunday and still no clots but at times still throughout the day my period has had a heavy flo. I am calling my OBGYN 1st thing in the morning, but wanted to see if this could be something serious? Thanks, Stephanie