PCOS, On Birth Control, Have Mint Greenish Discharge On The Last Day Of Menses. With Strong Sweet-sour Smell. What Could Be The Cause?

Hi, My name is Tess and I am a 15 year old girl. I ve never had sex, my personal is pretty normal; at the most I ve skipped three days without showering. I ve recently been diagnosed with PCOS (as in 7 months ago) and am on birth control to help contain it. My periods are now regular and normal, but toward the end of my period last month, when I took out my tampon , a very light mint greenish color appeared. It looked like a mixer of discharge and green snot... not exactly what I m used to seeing on my tampon! ha. It also had a strange smell too! I m used to the fishy smell, but this was like a sour smell but yet a hint of ...sweetness to it. I want to say it smelled of asparagus mixed with sugar. It was a strong smell too. Help me pleeeaaassseee and thank you!