<s>[INST] I ve been noticing bruises on my 17 month old daughters back, along her spine, for a few months. There s never been an exact reason for them and it s always only been 1 or 2 bruises at a time. I always assumed she had bumped her back or leaned on something. Today when I took her shirt off I noticed she had a lot of bruises on her spine, maybe 7 or 8. They aren t dark, I d say they are medium. Could she have low iron or calcium? Or could it be worse?? Every time I ve seen a bruise on her back my first thought was cancer. I m an over reactor and a worrier. But now that there are so many....? What could this be from?? [/INST] Yes, thanks for writing us, A bruise starts when small blood vessels in the soft tissue near the skins surface get bumped and rupture. When the blood seeps into the skin, it causes the familiar black-and-blue mark. Then, as the body breaks down the blood and reabsorbs it, the bruise typically turns a greenish-yellow. Bruises are more obvious on babies and younger child Chat Doctor.  They also tend to show up more on fair-skinned child </s>