Just a thought, are you trying to conceive? Could be a very early miscarriage, or whats called a chemical pregnancy, you miscarry even before a positive pregnancy test.
The small amount of heavy bleeding and clots could indicate this.
Hi,
Heavy bleeding, then spotting with clots I would say isn't an indication of implantation bleeding, I could be wrong however! But implantation is usually a very small amount that is a light pinkish or brown colour like old blood. Heavy bleeding or bleeding with clots would suggest your period.