Bronchiolitis: This is the most likely diagnosis given the age of the infant and the presentation of cough, bilateral creps (crackles), and wheeze. Bronchiolitis is a common lower respiratory tract infection in infants, typically caused by respiratory syncytial virus (RSV), and is characterized by these symptoms along with mild retractions.

Viral Pneumonia: Other viral pathogens can cause pneumonia in infants, presenting similarly to bronchiolitis but possibly with more severe symptoms or different radiographic findings.
Asthma: Although less common in infants, asthma can present with wheezing and cough. However, the diagnosis of asthma in such a young infant would require further evaluation and consideration of other atopic diseases.
Reactive Airway Disease: This condition can mimic asthma or bronchiolitis and is often considered in the differential for infants with wheezing and cough, especially if there's a history of similar episodes.

Bacterial Pneumonia: Although the normal CRP and the clinical presentation might lean more towards a viral etiology, bacterial pneumonia is a critical diagnosis not to miss due to its potential severity and need for antibiotic treatment. The elevated leukocyte count could suggest a bacterial infection, but the normal CRP somewhat reduces this likelihood.
Pertussis (Whooping Cough): Especially in areas with low vaccination rates or if the infant is too young to be fully vaccinated, pertussis can present with severe cough and respiratory distress. It's crucial to consider this diagnosis due to its contagiousness and potential severity.
Congenital Heart Disease: Although less directly related to the respiratory symptoms, infants with undiagnosed congenital heart disease can present with respiratory distress, including cough and wheezing, due to pulmonary congestion.

Cystic Fibrosis: This genetic disorder can lead to recurrent respiratory infections and wheezing in infants. While it's a less common diagnosis, it's important to consider in infants with persistent or severe respiratory symptoms.
Immune Deficiency: Certain immune deficiencies can predispose infants to severe or recurrent infections, including those presenting with respiratory symptoms.
Foreign Body Aspiration: Although more common in older infants who are mobile and putting objects in their mouths, aspiration can occur at any age and should be considered, especially if there's a history suggestive of an aspiration event.