My daughter is 15.5 and has stopped her periods since taking clindamycin and higher multivitamins for her acne and fatigue- about 4 months now- could these be the cause? She has since switched to clindamycin phosphate (about 6 wks ago) and has been taking propiotics and grapefruit seed extract - with still no resuming in cycles. There has been no change in her activity/stress levels. any thoughts?