Congrats sa fourth pregnancy, mama! Ang yellow/brown discharge with high PUSCELL count sounds like bacterial infection talaga, kaya good na you're on the metronidazole, a few of us mums had similar experiences and the suppository course usually helps within days, pero if it continues or gets worse after you finish the 7 days, definitely follow up with your OB agad because we want baby safe and healthy. Nakaka-anxious yan, lalo na after everything you've been through with PCOS and the previous pregnancies, pero you're doing the right things, hydrating well, taking meds on time, so stay positive! Sending you baby dust din, mama, and I hope this pregnancy is your rainbow moment!