Hopefully this was just a regular period........Are you sure you were pregnant? Most early term miscarriages occur around 6 weeks.
If you are losing tissue, that means a miscarriage, but you have to make sure that's what it is. Sometimes it's hard to tell the difference between an actual clot and tissue...some clots are big. If you call a nurse, they will say you are having a miscarriage if you are losing quarter or larger size clots, but they can be smaller when you are very early in the pregnancy.
Pardon my description, but I will try to explain: but a blood clot you can rub between your fingers and it will dissolve, and maybe feel a little rubbery, but tissue is harder and can be actually torn apart with a little effort. I guess you could think of a thick piece of kleenex? It's kind of like bloody skin and doesn't dissolve like a clot. I hope this makes sense.
I don't know if something whitish with red in the middle would be a miscarriage. The "baby" at that point is a small clearish ball, about the size of a small pearl. If that is what you saw, you may have miscarried.