Bram, I found this and while reading page 5 they talk about irritation of the ICB nerve, perhaps this is what you are feeling?

"Another cause of chest wall discomfort that prevents patients
from normal inspiration is irritation of the ICB nerve that
often innervates pectoral and intercostal muscles [13].
Involvement of this nerve is most often confused with
cardiac pain if it occurs on the left side and gall bladder
disease if it is in the right chest wall."

I hope this proves helpful and that you are felling better!

http://www.rsds.org/pdfsall/Systemic...ns-of-CRPS.pdf