I often experience these same pains and they are like between the breast and armpit. I also notice they get worse during PMS. I also suffer from panic attacks. This also increases during PMS.
I doubt that stress could cause that kind of pain. Could it be caused by a pulled muscle? As for the panic attacks, these are often physical, not psychological, in nature. Mine were cause by high cortisol (produced by the adrenal glands). Have yourself a thorough physical checkup with emphasis on finding the cause of your panic attacks. And ask about the pain you are having.
Even with anxiety, whenever a new symptom appears it's always best to see your doctor to rule out other causes first. This also gives you peace of mind which eases your anxiety. Take care.