The symptoms and findings are suggestive of dysentry
. You need to give him a full course of at least 14 days of antibiotics comprisisng ciproflxacin and metronidazole
. In the mean time he should eat only home cooked food and drink boiled water only. A 6 day course was inadequate.
Signs of normalcy are good apetite, no abdominal discomfort and normal consistency stools.