im not 100% sure but usually its just because your not changin your tampons or pads as much as you should be , the gross odor's indicate this as well
It is normal for vaginal bleeding to range from bright red to brown during a period, spotting, or pregnancy. Dark brown blood is generally associated with spotting or with the end of a period and is usually not a cause for concern. However, if you are worried or notice any different smells or symptoms, consult with your doctor.
Because it is old not fresh
Because it smells and is brown and mushy
you see if it smells of fish or not
The brown staining is your period this time around...
Its probably not from your period, its just probably poop stains. You probably don't wipe yourself good. :) I got it too. If it smells like nothing, then its dried blood before you get your real period. If it smells of poop, then it is poop!
your feet
it become gray and brown, and smells bad
my president is black my Ferrari is brown and smells like poo
Dark brown period blood usually appears near the end of your period.
See the related link on what causes brown discharge after period.
Possibly something to do with sulphur please see a doctor