pain in left arm pit and breast

I have been having pain in my left arm pit and breast and in my shoulder blade. It kinda feels like heart burn but, it is only my left side and at night time it burns really bad. I don't see anything nor do I  feel any lumps. Do you know what this might be?
Donna

[Cleveland Clinic]

Dear Donna:  There are many possible explanations for the pain you describe.  Most breast cancer is not painful.  Without evaluation, it is impossible for us to speculate on what may be causing your pain.  It is possible for heartburn to cause these symptoms but it would be important to rule out anything more serious, such as heart disease.  At a minimum, you should contact your doctor and make him/her aware of your symptoms.  If the pain is severe or unrelieved, travels down the arm or chest, or is accompanied by nausea, sweating or dizziness, you should go to the emergency room.

[Penda]

as I am well aware, your gall bladder is on the rt side, but (and NO I am not a DR,..just a person,..with a simaler complaint) But my pain was on the left,..and then in the middle, and when I would lay down, it got worse, if my diet wasn't watched,..with me they want to take out my gall blader because of gall stones,..have you notices indigestion, heartburn, and back pain,..and I guess it can have many symptoms,..I would suggest you look it up online,..and see if you think it could be a match,..and as always,..see your DR.!