My dad is getting over bronchitis&coughing a lot.he now has severe pain in his lower abdomen&low back, he had to lay down.coincidence or something new?

See a doctor: Coughing by itself can cause flank and abdomen pain due to repeated forceful muscle contraction. Worsening cough after a bronchitis is concerning. Many things can cause that prolonged cough. Some is more benign like post bronchitis bronchospasm or a more severe problem like pneumonia, pleural effusion or fluid in the lung. You should take your dad to see a local physician.