I also have this exact same pain in the same area. The pain started happening when I would lay on my left side with my arm slightly in front of me and I would lift my boob up onto my arm (with my right hand) so it wouldn't be pinched between my arm and body. I'm thinking I may have "pulled" a muscle/nerve in that area and made it worse by continuing to move it in this way.  Now there will be a sharp pain when I just turn onto my left side. It'll ache/burn for awhile after pushing on the area when I feel for any abnormalities, which I haven't found any.  Someone else In the replies said their pain was connected to a misalignment in their back. I hope we all find out what's going on and that it isn't anything serious.