Any idea? Pls advise.

by providing a pic without a proper question is hard for people to give an advice. was your lo born with these or are you asking due to your suspicious of him being abused? you mentioned you saw this on your lo back so I assumed these bruise are new to you? is he attending childcare? if so, you need to make a report and contact the school.

I’m so confused. Your LO seems like a toddler, meaning those are not mongolian spots, which you would have noticed in a baby. Sudden bruises? If not physical abuse, then something might not be right, you should seek professional medical advice

If its new and not born with it (some babies are born with “bruises” at their back), pls go doc to check or get medical report

was it sudden? or has been like this since birth?