It is common to get belly button infection and specially to those people who have deep belly button,as in you.
This happens because this is a moist and humid area,which favours bacterial as well as fungal growth.
You must consult a doctor and get the culture of belly button discharge and then taking anti biotic and antifungal medicines accordingly.
Rulebout the diabetes,as uncontrolled diabetes
results in increased chances of infection.
Try to keep the area dry and specially after bath.
I hope it helps.