Brief Answer: TEETHING. Hi.. Can understand your concern... As per your complain the problem of swollen and bleeding gums in your baby seems to be due to teething.. During the tooth eruption period of the child the gums of some toddlers are swollen ,sore,bleeding and itching. The gums keep breaking so that the teeth can erupt through them.. The same can be the cause with your sisters child too.. In some toddlers diarrhoea,drooling of saliva , irritability and mild fever can also be seen in the kids. What you can do is to massage the gums of the baby with your clean finger or a cooled rubber teething ring as it can be relieving for the baby.. You can wrap ice cube in a clean cotton cloth and place it on her gums to provide relief.. You can give her teething rings chilled in the refrigerator to chew on as it helps in relieving the itching sensation and urge to put anything in mouth. Feed your child with cool liquids and milk also in cool state to ease her discomfort.. If the symptoms does not improve you can consult a Paediatric Dentist known as Pedodontist. Hope your query is solved.. Thanks and regards.. Dr.Honey Nandwani Arora.