Answer:
Don't freak out, your not dieing... however you may want to go to the hospital. I had the exact same thing happen to me. Only I coughed and before I knew it I was doubled over on the couch gasping for air. I could feel my lower right rear rib muscles contracting to the point that it was hard to breath. This lasted for several minutes and finally began to let up. It was still very sore and I could feel the muscle when I breathed. I put heating pad on it for about 30 45 mins and this helped tremendously. Try to use warm moist heat.