From Where these thoughts come from?

Answer 1

Go and see a good psychiatrist. They can help.

Answer 2

If you are experiencing mental voices (thoughts) that are different than your normal little thought voice then you are hallucinating. A good way to tell is if they are unwelcome , multiple voices or of a different sex than your own. They may be derogatory or threatening if they are hallucinations. Where they come from no one really knows but one theory is Dopamine Dysfunction Disorder (DDD) commonly known as schizophrenia.