The correct answer is D. Treat with oral amoxicillin.
Treating the patient with oral amoxicillin (Choice 4) is the correct answer. The image shows an example of a presentation of Lyme disease. Please note the targetoid nature of the eruption, which can sometimes be masked by hair on the scalp, delaying diagnosis and treatment. Patients 8 years of age and younger should not receive treatment with doxycycline for Lyme as it is contraindicated due to the risk of permanent tooth staining and dental enamel hypoplasia. Amoxicillin 250mg TID or 20mg/kg/day in TID dosing for at least two weeks is appropriate.
Obtain a bacterial culture is incorrect as a culture of the ear for bacteria would be indicated if there is evidence of otitis externa. The earlobe and conchal bowl do not have any surface disruption or drainage for culture.
Increase antihistamines, applying cool compresses, or using acetaminophen can be used for supportive treatment but would not address the underlying cause.
Order bloodwork for Lyme borreliosis is incorrect because the patient has a characteristic erythema chronicum migrans eruption and symptoms consistent with early Lyme disease. Treatment should be the next step. Additionally, only 25-50% of patients will have a positive Lyme ELISA screen when they present with erythema chronicum migrans.