Chest pain under boobs?

I am 23 weeks and have had this severe pain in the center of my chest under my boobs above my belly, around the sternum area. It felt almost muscular and hurts when I laugh or move suddenly. It now hurts all the time and feels like my breast plate is breaking. I mentioned it to my doctor but he didn't seem worried. He said my organs are just shifting upwards... He also mentioned it could be acid from heartburn. Has anyone else experienced this? Anything that worked to help with the pain? I've tried tums and Tylenol but could use other suggestions.