Hi there -
We will be moving this post to a more appropriate forum, but please get this checked out promptly if you haven't already.
Usually when there is pain associated with movement and/or breathing it can be related to costochondritis and that causes pain in the lower rib area or upper breastbone. The condition is inflammation that can be on both sides of the sternum (junction in the middle of the chest), but usually on one side only. The pain may be greater when in sitting or reclining and moving positions. That is an insight into a possible probability, but a heart condition can not be ruled out.
Other possibilities is pericarditis and that is inflammation in the area of the space between the heart and the surrounding sac. A respiratory problem can cause pain when breathing due to blood clots in the pulmonary vessel and or the lungs....that condition causes chest pain. Nevertheless, Emily is correct, and hopefully the information provides an insight that will enable you to discuss the issues in consultation with your doctor. Even if the pain subsides you should still contact your doctor to rule out any damage and/or a condtion that may only be in remission.
Thanks for sharing, and if you have any further questions or comments you are welcome to respond. Take care, and I wish you well going forward.