What Causes Vaginal Spotting After A Stillbirth?

I am 5 weeks post partum. I had a premature baby who was born still born at 24 weeks, weighing 8.5oz. I had a vaginal delivery, no complications other than preeclampsia during delivery. I had the postpartum lochia for 2 weeks and it completely stopped. Only complication was endometritis that was treated with Doxycycline for 10 days. Tuesday of last week, I went to restroom and there was a scant amount of light pink blood with increased discharge, only when I used restroom (one time that day) this was the same for Wednesday and Thursday. Friday - Sunday in the morning for about 3 hours there was brown *only brown, no red* when I used restroom. Today light red/brown blood, again flow is very very light - I would consider spotting, only when I use restroom. Flow is not heavy very very light, merely using a panty liner that contains no blood. The spotting is only when I use restroom and clean myself afterwards. Since my baby passed, I am not breastfeeding or expressing. I had my 2 week postpartum check and was given the okay to start trying to conceive again, since I am almost 35. My question is, is this bleeding considered my first postpartum cycle or ???