What Causes Pain Under The Ribcage And In The Sternum?

Hi, I am a female 33 yrs old and have recently started having RUQ pain. I was having a nagging RLQ pain off & on before this, I do rarely get occasional nausea and I've always suffered with constipation. I recently had a CT abd.& pel.w/out and everything was okay from what it showed. This RUQ pain started 2 days ago and it can feel sharp at times and it's just underneath the rib cage on the right side and now sometimes in the middle below the sternum. It seems like pushing on it or taking in a deep breath can make it more noticeable and painful. Any ideas as to what could be causing these things would be so helpful?? Thank you!!!