What Causes Blood Stained Vaginal Discharge?

Hello. I've already had my period this month. I've been really sick for over a week and noticed that I had blood in my vaginal discharge. And I was wondering if the intense coughing could cause the bleeding. I've coughed so much that I have a stitch in my side that is painful and thought that might be associated with the blood. I appreciate any advice you have. Thank you.