Typically when a person's side hurts it is coming from a pulled muscle. When they go to cough, they are using these muscles to do so which can make the side hurt worse. There is not much anyone can do for a pulled muscle. It will heal over time with lots of rest. Try not to do any physical activity while the muscle is healing. If it continues to be a problem, they should see a doctor to make sure there is nothing more severe going on.