There are no ghosts, only demons. The Bible says: For the man will live once, and after that he will face judgement. It also says: to be absent from the body is to be in front of the Lord.
Demons are the spirits of the hybrids and nephilin, they are the spirits of every creature God did not created, like hybrids, offspring of the fallen angels, etc.
Most of the so called mind enfermities are demonic possessions or opressions. Depression, adction, anger, all of these are signs.
If your voice changes and you start saying things that you do not want, this is also a big sign.
The authority of Jesus Christ can cast out any demon, just use it.
This happened to me during puberty. Demon confirmed.
A friend of mine had a demon once. She gargled some salt water for a few days and kept hydrated. There's hope for you.
I've also heard that vitamin C is an effective demon repellant. (BTW if you are gonna gargle saltwater, you should always have a teaspoon of honey added, it makes it a much more pleasurable experience)