What Causes Abnormal Periods After C-sections?

Hi, iam 34 years old i have three kids all born with c/section delivery after the delivery of my third baby who is 13 month old i was bleeding for 70 days continuously which i wasn't used to, then i had my first period after six months from the time it stopped so far i had 3 periods the first two were fine last month my period lasted for 14 days, it was red till the 12 day and then brown the last two days by the way it didn't stop for one day. this month i have brown discharge yesterday and today looks like what i have toward the end of my period which is not how my period usually start iam not even sure if it is a period or no. what is going on with me iam worried should i be?? Thank you.