When I breathe deeply, I feel quite sharp pain in the back of my left lung/side and a smaller amount of pain in the front of my left side just below my heart. I am a 19yr old female and I dont smoke or drink, although I have lived my life around a smoker. This pain started last night randomly and came literally out of nowhere, it hurts when I change position of my left arm but its not muscle strain as I havent done anything strenuous to my body. The pain lessens when I am laying on my left side and breathing deeply, but if I lay on my back or on my right side it goes back to how it was before. Please help, its a Sunday and my doctors arent open today so I have to wait until at least tomorrow to get it checked out.