Thanks for posting your query at DoctorSpring.com
I can understand your concern. I reviewed the picture.
It does look like Lyme's disease in the picture.
My other differential diagnosis would have been ringworm with secondary infection. But since you have already provided me with the necessary information, I would recommend visiting your doctor at the earliest. The treatment would be taking doxycycline , an antibiotic for it.
Please let me know if you have any queries.