“Minor soreness below sternum when touched or pressed?”

Hello, I was kinda concerned about this mild soreness I have in the mid-section of my topmost abdomen. It's not widespread, just in a small area. I've also noticed that my shoulders and back have been sore as well and occasionally, my left wrist would slightly ache. The weird thing about this is, I'm able to breathe, eat, drink, swallow normally, laugh, talk, and sleep, and also quick aches around my heart as well. I work in the shipment department in retail also, so I just wanted to know if this is from muscle strain or do I need some sort of diagnosis. This mild soreness also started Tuesday night when I began pressing into my abdomen, the night when I had just left work.