Confused..

I woke up this morning I'm supposed to get my pd today and I had some light brown pinkish substance on my panty liner (I wear a panty liner all the time it's easier to check C.M.) then it just stopped. I took a pregnancy test about 3 days ago and it was neg. Could it possibly just be the start of my pd? I had a c section in January but unfortunately my daughter passed a few hr after she was born and my husband and I have been trying for our rainbow baby. I don't know if having a c section would affect me having regular pd. Someone help?