First of all, congratulations on your child - I hope the delivery itself was not too difficult.
I will assume that you are not breast-feeding given the initial resumption of your cycles. I will also assume that you are not on any form of birth control or I think you would have mentioned that to me.
It is not uncommon after the birth of a child to have irregularity in your cycles related to unpredictability of when you ovulate. In women who are breast-feeding, or even in cases of being around a crying newborn, there is elevation of a hormone called
Prolactin. When this is elevated, cycles can be irregular or non-existant.
In the case of a light brown discharge, this might be related to a small amount of
breakthrough bleeding related to the irregularity in your cycles. Here is what i would recommend:
1. If you have had
unprotected intercourse at any time since delivery, do a home
pregnancy test. If it is positive, then contact your OB/GYN
2. While I am saying this is normal, if you are concerned about the irregularity, temporarily being on birth control is worth considering for cycle regulation.
I hope this helps and good luck!