A bump inside a nose piercing is caused by an infection from the choice of jewelry or granuloma due to overgrown tissues. According to Beautyhows, granulomas are not caused by infections, and they generally clear away after sometime without the need of medication.
Fake jewelry such as rings, nose studs and screws can cause infections, leading to bumps in the nose piercing. It is recommended to wear quality jewelry made from genuine materials such as titanium and niobium, states Beautyhows. Generally, bumps in the nose piercing are not harmful. However, if they are persistent, consulting a doctor for a medical examination is recommended.