Thanks for posting your query here.
Based on your description, it seems the rash has been ongoing for too long as compared to what I would expect in a simple viral rash
(He doesnot fever
or other symptoms as well). Again, lymph
node swelling as you mentioned in the neck should start to settle down by this time.
I would suggest he needs to reviewed by Pediatrician
again and blood testing is needed based on clinical examination findings.
Do revert back to us if you have any further queries.
Dr Tejas Shah