For a 7-month-old, oral cough and cold medicines like HH Linctus and Nuhist are not recommended due to potential serious side effects in infants. Since these medications haven't worked and his breathing is noisy during feeding and sleep, please stop them and consult his pediatrician immediately. A doctor needs to examine his chest to rule out conditions like bronchiolitis. For safe relief, continue using Nasoclear saline drops followed by a nasal bulb aspirator to clear his nose before feeds, and use a cool-mist humidifier in his room. Seek urgent care if you notice rapid breathing, chest pulling in, or if he refuses to feed.