I am bleeding before my period. it started of dark brown sludge like for 3 days and then red. period not due for 7 days. slight cramping. ?

Well: Sometimes the periods get off due to irregular ovulation. Are u on the pill? Assume ur not, the "sludge" is likely old blood/ endometrium. The menses may right itself but age could be a variable, weight gain, etc. With neg pregnancy test don't worry. Age makes a difference in what is done, if 35 or older and bleeding more heavily u may need sampling of endometrium to rule out endometrial cance.