I took levonelle a week ago and today i started having a very dark brown watery discharge. my period isnt due for another few days,should i be worried?

Levonelle is a: ...hormonal "emergency" contraceptive that can prevent pregnancy after unprotected sex. In works primarily by interfering with the hormones that trigger ovulation. However, it can have other effects on the menstrual cycle, such as those you're experiencing. This period may be off schedule, but your next cycle will be back to normal. So, no worries! Dr. Anne