A 32-year-old man from rural Maharashtra presents with a 3-month history of productive cough, fever, and weight loss. Chest X-ray shows cavitary lesions in the right upper lobe. Sputum smear microscopy is positive for acid-fast bacilli. He is started on standard first-line antitubercular therapy (RIPE: rifampicin, isoniazid, pyrazinamide, ethambutol). After 2 weeks of therapy, he develops acute onset painful red nodules on the shins and fever. What is the most likely adverse effect?