What you should do is try to contact the gods and ask the gods for help. If this is something good like a god or a family member assisting you, then good. If it is anything bad, the gods will protect you and remove it.
In recommend don't start trying to harm or banish this thing right away on your own without knowing who it is, because it might be somebody good who is helping you. Any time you are unsure, ask the gods for help.