Hello Welcome to HealthcareMagic forum . Usually stomach infections are associated with diarrhoea rather than hard stools. Constipation is common in toddlers and more common in formula or cow milk fed babies than breasted babies. If there is a recent change in her milk or diet try to avoid it for a couple of days to look for any correlation ans self resolution . Drowsiness can be due to various causes , inadequate hydration , infection, lethargy etc If it persists do get your child evaluated by her pediatrician promptly. Meanwhile you can try the following , Increase water intake . Try diluted cows milk or preferably formula milk if breastfeeding isnt an option. Avoid apples , carrots etc which may aggravate constipation. Try leafy green vegetables or fruits ( soups , mashed , juice etc) to increase fiber intake . If nothing works ask your doctor for prescription laxatives and digestive suspension ( lactulose , PEG etc) . Wishing your child good health. Regards