DH's cousin's infant has RSV, which is prevalent among babies and toddlers and causes an everlasting cold with accompanying congestion. Poor guy!
Thank goodness for my daycare providers who called me one day when DD#2 was about 3 months old. They were concerned because, when they changed her diaper, they saw that her chest was rising in a jagged motion when she took a breath, not smooth as is normal.
I took her to the Dr. and they immediately hospitalized her. I spent 2 nights and 3 days with her while they gave her medication through a breathing mask every two hours*. Then, when she came home, a therapist came to our house and taught me how to give her the medication which she was on for about a week before she was 'cured'.
Interesting that you say "everlasting cold" because she never showed overly congested cold symptoms. However, later in life (in High School), she was diagnosed with asthma. I never made the connection!
Hopefully your cousin's little guy will come out okay without any long lasting effects.
*This was 22 years ago, things might have changed since then.