A 32-year-old woman from rural Odisha presents with fever, chills, and sweating for 3 days. She reports a 2-week history of travel to a malaria-endemic zone. Physical examination reveals hepatosplenomegaly and mild jaundice. Blood smear shows ring forms and multiple ring forms within a single RBC. She is started on chloroquine 600 mg base stat, followed by 300 mg at 6 hours, then 300 mg daily for 2 days. On day 3 of therapy, she develops severe pruritus, urticaria, and angioedema. What is the most appropriate management at this point?