I feel like i have trapped air in my back causing pain... is there any at home remedy i can do to fix this?

If you have no abdominal pain, neck pain or problems breathing, then a pain on the back side of your chest is most probably muscle based. (Costochondritis) It could be a strain or a pulled muscle from new exercise, lifting something heavy or reaching too far. Take Acetaminophen every 4-6 hours, rest the area, and apply ice as needed. If pain worsens or you develop difficulty breathing see a DR