Advice

Can anyone offer a bit of advice. My Little boy is 4 nearly 5 months old, this past couple of days he’s had a really barky cough , it doesn’t seem to be bothering him to much and this is his only symptom, he doesn’t have a runny nose etc ? I’m so confused to what it could be. Am I better contacting a doctor just incase to get it checked or if he continues to be happy enough just wait and see?