Hi I can understand your concern.... Let me know you your both child diagnosed pneumonitis means inflammation of lung tissue .... If consolidation and exudation present then it could be pneumonia .... But here consolidation not present ... Cause has to be searched like ..... /Viral infection which seems most likely here /Passive smoking exposure /Hypersensitivity pneumonitis means allergy to certain substance like animal dender /Bacterial infections etc...... Your child should be examined and treated accordingly with steroid or antibiotic usage .... Consult pulmonologist for this.... Hope your concern solved .... Take care... Happy to help you further....