Could this be breast cancer? :(?

I am 20 yrs old and I have a really painful left breast pain, hurts to breath,sneeze,cough,hiccup,yawn. at first It didnt hurt that much and after the 3rd day I can't even breath. It even hurts when im just sitting regularly, but it will not go away. My left nipple also is abnormal to where its more oval shape than just round like my right side. I've taken beyer's aches and pains medicine and also tried putting an ice pack on it. It did not help at all:( can anyone please tell me what this is? I thought i felt a lump but im not quite sure if its just something else.