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You are in a central Virginia ED seeing a 16-year-old boy with itchy hives, stomach cramps, vomiting, and mild angioedema of his lips. He is not wheezing, his vital signs are normal, and his airway is patent. His diet history is as follows: glass of orange juice and leftover cold pizza at 9am, half-pounder burger with bacon at noon, and a PB&J (which he eats daily) at 3pm. Symptoms developed at 3:30pm. Review of his medical records reveals that he was seen in urgent care for an embedded tick 1 month ago, and again for strep throat 8 days ago – he is on day 8 of 10 of amoxicillin to treat his strep throat. He received no antibiotic prophylaxis after the tick bite. 

Which of the following is the most likely cause for his symptoms?
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