My 4 month old has a cold, when should i worry or go to a doctor?

URI in an infant: is a common illness, and should be evaluated if your infant is eating or drinking less than half of normal, has a fever more than 2-3 days over 101, has rapid or labored breathing, is very irritable, or if symptoms last more than 10 days. Fever at onset of a cold is common, usually resolves and symptoms usually improve gradually over a week, but if symptoms worsen, a secondary infection is likely