I have a caught that's been lasting over a week now and every time i cough my kidney hurt. i also have bad kidney working at 30%?

Cough and pain: Your pain on coughing is due to your muscles involved with the cough process. If you have that bad a cough, you should see a physician and/or get an x-ray to make sure you do not have a pneumonia. Your poor kidney function (kf) of 30% at your age is concerning. Have you seen a nephrologist (n) to see what the cause it and if your low kf can be improved? Good luck.