Hi
The area at the belly button is deep, moist, warm , contain loose skin fold and is easy to get assessed by hands of children. Also in this age group children put their contaminated fingers at this site repeatedly and more while playing. So this area becomes prone to the infection. Now infection can be bacterial or fungal type, depends on the symptoms and signs that has to be looked. In your case as you are saying there is itching and sometimes bleeding both of these symptoms can be caused by any type of infection. However, bacterial infection is ussually associated with pus discharge, more pain tenderness, redness , swelling and symptoms will increase if not treated. The other type that is viral usually has mild symptoms lesions can be circular , scaling of skin may be present , itching is so severe it can result in bleeding. Treatment is easy for both the types. Also hygiene has to be maintained. After an age she will not play or put the finger into belly button the problem will be least likely to appear.