What Causes Painful Rash And White Discharge From Vagina?

Hi there , in the past 4 days me and my partner had sex in the morning I woke up and I had a rash at first it hurt a lot. Yesterday I found out I had some white stuff inside my vigina , I didn t pay attention to it I thought it was some cream I had put on it. Well today I checked again and the white stuff was still there it seems like my whole vigina is filled inside with it ? I got really scared?? What can this be!