Hi ~ OUCH! That sounds painful. You could have strained some tissue in there, or actually you COULD have cracked/broken a rib!!! There isn't alot they do for broken ribs, but if it IS broken, you have to be careful that it doesn't puncture a lung. I've broken a rib before, and/or strained that area, and it helps to wrap yourself with an ace bandage or use some other device to give you support. After I wrapped myself, it didn't hurt so much to take a breath.
I wish you the very best -- I hope you heal soon! God bless & take care. Hugs, Lee