sour smell

Month after I gave birth, I've had my period agad. So yung sa brgy. center nag advice na sakin na magpainject or magtake ng pills. Since breastfeeding ako, pills binigay sakin. After that 3 months akong walang period. Ngayong mag4mos na si LO nagkaperiod ako pero mahina lang, panty liners lang nga gamit ko. Almost 1 week na ganun. This morning lang meron uli lumabas sakin mejo brown siya and it has a sour smell ? Is it normal ba mga momsh? Bakit kaya ganun? First time lang to ih.