This could be wrong, however I have pain under my left breast/ribcage and I have heard that is a symptom of IBS.
Ugh i have the same exact pain!!! I've had it for three years now since i was 18 and it's the most uncomfortable thing to deal with. It is a constant sharp pain and rarely goes away. I have been to so many doctors and they say to not eat spicy foods also but it never even made a difference as the pain is always there. The most recent doctor said it was severe IBS which has symptoms of pain under breast on left side. I wish i had medicine or something that helped it. Hopefully your doc will help and you will feel better...that pain is not fun. Feel better!
It is also a sign of red blood cells rupturing the debris clogging the spleen.
Is it dangerous or life threating