What could be the cause of a black and blue mark on my upper back?

Answer by  thom0045 (350)

If a person has an unexplainable black and blue mark on their upper back, it could be bruising due to a lack of potassium in the body. If a person has a bruise like this they need to eat more potassium; eat bananas!

Answer by  janu (53)

It could be any blood vessel related problem or strecth marks. So I suggest you go to doctor as soon as possible and get it cured. Dont neglect it and face further complications. I need extra information about it to explain you like did you ever had injury on upper back? or do you have diabetes or b. p or any blood diseases?