I had asked for some further information and have not heard back.
Whenever someone is having chest pain, the usual recommendation would be to be seen in the ER. This is because one of the possible causes of chest pain is from the heart, which is the one cause of chest pain that can be acutely life threatening. Once an appropriate evaluation has been done to exclude heart disease as the cause of pain, then it would be appropriate to consider other causes of chest pain.
There are a couple of common causes of chest pain that is worse with a deep breath. It can be related to conditions in the chest, which can be infectious or inflammatory. It can also be related to musculoskeletal inflammation in the rib cage. In this latter case, there will commonly be tenderness when pressing on the area of inflammation.
Certain problems of the GI tract also can cause upper chest pain, such as acid reflux and esophageal spasm. It is not common for these conditions to have exacerbation of the pain with a deep breath, but while the worsening with a deep breath makes these causes less likely, it does not exclude these causes of chest pain.
Although it would require a proper evaluation to determine the exact cause, there are a couple of home interventions
that can be considered once heart disease has been excluded. It would be reasonable to take an over the counter anti-inflammatory medicine, such as ibuprofen or naproxen.
If I can provide any further information, please let me know.