Positive pregnacy after aunt flow...how so????

So i seen AUNT FLOW september the 21-25 its strted out pinkishh four hours then worked its way being red as normal....no cramping no clots just sore breast and alot of eating...i.asume it was aunt flow due too the smell???so i used tampons as usual and pads sometimes still no clots....as the 25 aproched it began too be brown spotting???went to the docs yesterday they test me POSITIVE as well.....Wats going on ANYthinG ladies.......