What Causes Brown Vaginal Discharge?

Hi, I had my period on Tuesday 24 - Friday 27. Yesterday was normal but then this morning I woke up with a stinging sensation in my vagina and as I went to go to the toilet, it stung a tad bit more when I urinated ): as I wiped.. I saw brown bloody colour .. As of this moment inside my vagina is yellow discharge and when I wipe it s still brown ! Please help !