It might be umbilical granuloma. You might need to clean out the content from your umbilicus, followed by ointment application and antibiotics. Povidone is alright but just applying it without fully evacuating the granuloma won't be effective.
Next Steps
Try cleaning the umbilicus with a sterile gauze and some saline. You can also take a consultation with a specialist ( general surgeon or Plastic surgeon)of your preference to guide you through the process if you find it difficult.