5 Yr Old Boy, Congestion, Unproductive Cough, Given Expectorant Every

5 yr old boy, congestion, unproductive cough, given expectorant every 4 hrs per instructions. He is still coughing, it is disrupting his sleep, he fell asleep and woke up 2hrs later coughing and has not been able to fall back to sleep due to how often he is coughing. No fever. What do I do now?