Hello. I Am A 17 Year Old Female And I

Hello. I am a 17 year old female and I have constant pain of my ribs. Especially in between the breast where my ribs "meet". The pain is dull when I am laying down or sitting up, but the pain becomes worse when u try to sit up from the lying down position or if I am propped up with my pillows. Do you have any idea what is going on? This has been happening off and on since I was 14 and had bronchitis for almost 2 months