This has been going on for a few months . I get sharp pain under my right arm pit about 2-3 inches down. Its on my side under my arm pit 2-3 inches down my side .When it hurts it's when I breathe, heart beat , just seating . It's only every so often. I only have 1 kidney, my right kidney . It's functioning about 36% . I also have chest pain on my right side . It hurts at times when I have my bra on . I don't think it has anything to do with my kidney . But I don't know what it is .