So I Am On The Implant After I Had My

So I am on the implant after I had my daughter 17mos ago. I haven't had my period since but once like 6 mos after the birth & it lasted the normal 3-4 days. Now I am on my period again as it's been two weeks and it's coming out like clumps and it stopped and came back.. It continuously is doing it during the day going on and off! And the cramps are terrible. It's really scary! Is this normal? Could I be experiencing a miscarriage?