Creamy white discharge with a little blood mixed in it. 2 days since this has happened and before that got a brown discharge (once). what might this be?

Infection? STD? Any new, abnormal, unexplained vaginal discharge should be professionally evaluated. Many possible causes, but "creamy" or brown discharge, or blood, suggest infection -- and at your age (18) that often means an STD like gonorrhea or chlamydia. See a doctor soon. Good luck!