I too would encourage you to suggest that they get their son (along with that picture) to a LLMD to be sure it's not a bulls eye rash. If there is any clearing near the center, please have them continue to take pictures to show how it's developing.
I was only 7 when I was first infected, and let me tell you - growing up with these infections is horrid. It sucks the life out of your life, and as a child, that's miserable. Use my story if you wish, you can direct them to the post in the link below if you wish, it's a really short version of my story.
Herb only treatment for Lyme & Bart ended 12/11 - no active symptoms for 2 yrs -Herb only treatment for Babesia ended 12/12www.healingwell.com/community/default.aspx?f=30&m=2977364
Had Lyme, Bart, Babs, RMSF, Ehrlichia, Myco, Anaplasmosis, EBV
New Lyme case 8/2014 - Healed 1/31/15 - unknowingly had Asymptomatic Babs and Asymptomatic Bart, being treated now though (2/2016)