M.6.
Unless you are experiencing a foul odor, fever, or clots larger than say a golf ball, I don't think you have anything to worry about other than mentioning it to your doctor at your next appointment. When you nurse, your uterus contracts, which can cause irregular bleeding for quite awhile. Plus, it is unlikely that you started your "regular" menses at the 5 week mark as usually lochia lasts 4 - 6 weeks after childbirth.
Good luck!