If your back causes you pain you may have one of a number of conditions that I would prefer to not guess at since I’m not a qualified health professional. If you’re really concerned then you should consult your doctor about it and find out if there are any problems. Spines don’t always grow the way they are supposed to. Really nothing in the human body always grows the way it’s supposed to. If the genetic defects are significant we may called them a deformity, but really we all have some deformities. I know a girl with extremely long toes for example, and my own nose is probably bigger than it has to be, especially since my sense of smell is quite poor.
If you’re especially thin your spine may be very much like the majority of people and could just be sticking out as much as anyone’s, except that you would have less flesh to cover it up.
If you are referring to a single place where your spine sticks out you may have some kind of injury, or a potentially problematic spinal deformity, which is fairly common. In any event you should most certainly consult your doctor if this is the case.
