Hi Ashleigh V!
How are u doing? As Jo said, it could be a nerve. But I also experienced the same thing too. Its funny that you posted this today cause i actually experienced it this morning when i was in bed. I used to have this ever since i was a little girl. I remember getting an ultrasound cause i was so scared of it. But, it is just gas. It feels like gas bubbles pushing right up to your ribs (near ur heart). And it hurts when u breath in...right? Ya, thats exactly what happens to me.
I never knew what to do to make it go away, so i would panic cause I would have trouble breathing. Anyhow, i know what to do now!!! Basically, since u have gas pushing up there, you need to stretch that area. So you can raise up your hands and just stretch out your chest. If the pain is on ur left side (near heart). Stretch out ur chest back and to the right side.......that way you are giving the left side a nice big stretch. U will find that it will go away after the stretch. Try it and let me know if it goes away.
But dont' worry, its nothing serious. Trust me, i have had this almost all the time. Just do some stretches!
I hope i have helped!!!!! bye for now!