Mucus in chest, congestion, sound.

You definitely have some allergic tendencies . What you are describing seems to be like a mild asthmatic attack . You will have to identify the allergens and try avoiding them . Viral infections are a common trigger for allergies . Whether this has happened in your case or it is due to the  intake of juice and ice cream it is difficult to say . Both could have been contributory . As far as your son is concerned , if he has inherited an allergic tendency from you that will be with him the way it is with you . Isolating has no role . Viral infections are readily transmitted from one family member to another . Total isolation is not possible in the home as other members get it from the air . However you may avoid very close quarter contact like kissing , hugging , sharing food etc till cough and Nasal discharge settle .