Thank you for your query.
I am afraid I have not heard or read anything about "walking pneumonia". I shall appreciate if you can provide the exact diagnosis.
It is good to know that your son is responding to the antibiotic and the fever
has come down.
It is difficult to comment on the redness
along the spine without having a look at it. In case it increases it is better to consult your doctor who shall examine your son and guide you accordingly.
I hope I have responded to your query to your satisfaction.
Wishing your son a speedy recovery.