Back pain is often insidious, i.e. no obvious cause such as an injury. This can be due to a slow process of sensitisation occurring sometimes over weeks or months. This is frequently a complaint of the sedentary worker (i.e. desk bound for long periods) but also those who move in a repetitive pattern, have to hold sustained positions or in the case when a normal movement triggers pain.
Pain can vary in intensity and description but is deemed not to be an accurate indicator of tissue damage. Therefore, it can really hurt despite there being little in the way of an injury. Pain is a warning sign of potential or actual 'danger' to the tissues, so you are right to take advice, that's the whole point of pain, to motivate an appropriate action.
The area described appears to be about the ribcage and if there is sensitivity to movement of the chest wall then breathing will be challenging, especially if deeper inspiration is necessary. The sense of feeling winded is therefore not unexpected.
The best course of action is to see your GP or a musculoskeletal physiotherapist for an assessment and subsequent treatment/management plan.