Just after my peiod I have pain on my right under rib cage?

Catamenial pneumotho. While the association between menstrual periods and chest pain is more usually coincidental , catamenial pneumothorax needs to be ruled out . Would recommend to talk to your doctor, and if necessary a pulmonologist . Catamenial pneumothorax is still a rare condition and in your case anxiety associated with menstruation might also be possible.