Freaking out

I'm having blood clots. Like a lot. I'm 20 weeks pregnant. I'm freaking out. Went to the doctor and he said I'm fine and sent me back home. The blood is starting to loosen up and is looking like a light period. I've had miscarriages before and I've never had this happen before. Am I having a miscarriage?

UPDATE: Okay I went to a different doctor as soon as they opened and I'm suing my old doctors office on suggestion of my new doctor. I'm pregnant with twins and they are big and it's more common to spot when you're pregnant with twins. And since I have had previous miscarriages the bleeding was heavier. I eventually did stop bleeding and I'm back to normal. The whole time I kept telling my old doctor it looked like there was more than one baby and hey always said no. Both of my babies are healthy and I'm going to start taking pregnancy safe vitamins. Now we just have to buy more stuff for the nursery😂