My husband is passing black stool. The stool is normal & sticky (but not loose). Also, he's feeling lethargic and weak. Although, he's not having constipation. The stool is clear everyday but it's black in colour. He's having Veloz D in empty stomach and his water intake is little less due to busy office schedule. 2 months back also he had the same problem but he had Veloz D for 7 days and alot of water and fruits & this problem was gone. Please suggest what medicine to give. Next course of action.