Bruising

I am having a panic because friday I noticed some Mark's on my 15 month old spine. It looked red and like bruises. Now here it is sunday and it is definitely bruises. I feel like a horrible mother because I do not know how she got it. I was with her the entire time and never seen her fall or hit her back on anything. Has anyone else experienced this with their littles before??

I have already notified her doctor and she is super active. I have taken pictures every day of it as well.

Update.. her ped refused blood work and said it was from a traumatic fall where she would have been hunched forward. He is having us do an xray on her spine to check for damage. Since it happened Friday and was seen today there will be a call to dcfs.