What Causes Abnormal Menstrual Discharge And Abdominal Bloating Post Medication For PCOS?

Hello Dr. i am 26 yr old single. going to wed next month. Having irregular periods problem ultra sound scan showed positive for PCOS. doctor prescribed meprate (tablet 2 for 5 days) after a week got dark grey to brown discharge for 2 days but mild only no regular bleeding always feeling bloated cant take enough food and my allergic symptoms got worst what could be the reason for all those things?