Lungs hurt when taking a deep breath. what is the issue?

Vague Question: Pain with deep breathing could be either a cardiac(heart) or pulmonary(lung) issue. Either one is not necessarily a good thing and you should probably seek evaluation from a local physician because worse case scenario could be a life threatening event.

Pleurisy: If you chest wall it not tender it is likely to be pleurisy which is an inflammatory of membranes covering the lungs and lining the chest cavity. It is often related to a virus but it would be prudent to have it evaluated.