What Causes Spotting With Foul Odor After Periods?

I noticed that after my menstrual cycle last month. I had a light brown discharge with foul odor. I've never had this problem before. I went to see my ob-gyn about 2 1/2 weeks ago and advised me to douche with vinegar and water. He also gave me a prescription which I never filled. The foul odor went away but it's still not the same. There's still this odor. Should I go ahead and fill that rx?