What Causes Pain In Chest And Abdomen While Taking Deep Breaths?

I'm a 24 year old female, somewhat overweight but fairly active. About a week or so ago I had some sharp pains in my chest and abdomen on the right side when I would inhale, which was worse when I took deeper breaths. It got better and would only periodically hurt (perhaps mostly when exerting my lungs in exercise). Today I noticed that my right collarbone area has soft, spongy/lumpy tissue over the bone. On the left side I can clearly feel the bone structure, but on the right side I only feel this soft tissue.