Could Fractures In Ribcage Bones Be Due To Severe Coughing?

My 7,8 back rib fractured Jan. 11,2015 when I was coughing.My adult son decided to help me by flapping my arms up and down telling me I should work it out. I told him to let me go that i indeed broke bones.I received a cat -scan that showed that these fractures are caused by blunt force trauma. Nobody or nothing has hit me .I felt the bones break when coughing.