Thank you for posting
Initially your son must have been having a viral respiratory tract
infection but I do think presently that is possible that he is having but bacteria respiratory tract infection known as rhinobronchitis. Also important for him to be reexamined by a pediatrician
to rule out typical pneumonia
(as it can also be possible). At this point your son will require in addition to the above medication a course of antibiotics to fight the bacterial infection. So to do now, is revisit your pediatrician so that the child can be reviewed and appropriate medications given.
Most at times it is difficult for a viral resp tract infection to relapse, there is usually super infection with bacteria.
You need to consider this an urgent situation
Hope this helps