Took plan b had my period on time. had -ve tests. after 16 days started having pms . is this another period ? is it normal to havke 2 periods 3 week

Probably: It is not unusual to have menstrual changes after Plan B treatment either with heavier than normal bleeding or early periods. Plan B also has other side effects including abdominal pain, breast tenderness, nausea and dizziness. If you dont resume regularity in your cycle in a couple of months, consult your gynecologist. Make sure you to resume regular birth control to prevent unwanted pregnancy:)