I Have A Slight Twinge Of Pain Underneath My Right

I have a slight twinge of pain underneath my right breast, I can't feel anything external it's something on the inside. It kind of feels like I pulled a muscle somehow at the bottom of my chest. This pain reminds me of what some people have told me having a cracked rib feels like. I'm on a crash diet right now and have been drinking a lot more water than I'm used to, taking Metamucil twice daily, diet drops that go under the tongue, and just eating a low calorie high protein with some fruits and veggies diet. I'm 25, female, I've lost 11 lbs in 1 week