I thought I was sick with the stomach flu because of having diahrea for 3 days so stayed home then cramped from my period on my tampon was a weird grayish thing and felt one dropping out thought it was a clot at first but looks so different could it be a miscarriage? Also if it was is that it it's gone or need to have the doctor finish it?

Very early miscarriages are common, possibly more common than any studies could really show without a great deal of expense and monitoring, and the fetus is very small and often not even noticed.
But many women do find quite large clots of menstrual lining of various colors that aren't bright red too, just because they have been exposed to air.
You shouldn't need a D&C. There isn't enough time passed to develop much lining.
(If you did have some left in there, you would soon get a fever.)

Thank you!