I have an enlarged vertebra, middle of back, not sore or painful. Only noticed this two days ago.
Do you mean you can see a more prominent "bump" on your back from the bone sticking "out" of the skin?
Is this where your neck meets the shoulders? Or the thorax/chest area? Or lower back?
a more prominent bump middle of back, one of the vertebra
This should not be anything to worry about.
Unless there are symptoms of pain, numbness, weakness, usually the back is not imaged. You are probably just noticing the prominent "spinous process", or piece of the bone that often can be seen and felt in more slim people.