4 y.o. with bad cough

3 weeks ago, son had strep A. Prescribed antibiotics but on 8th day, he developed hives. Allergic to amoxycillin. He had a light cough now and then. Then a few days later, he complained of stomach pain around the navel. I didn't think much of it. He had polio vaccination. Developed fever for 2 days and then the cough worsened. Cough went away for one day and then came back worse. It's wet cough. Worse upon waking. He also coughs when he's asleep altho' not as bad as when he's awake. He still complains of stomach pain. Doctor examined him before the cough worsened and said his lungs were clear and she could not find any reasons for the stomach pains. What should I do? I gave him pulsatilla 200c because he was very clingy and whiny to me but the cough has not improved.