In my experience of paranormal research, if there are 3 knocks usually between 3am and dawn, it's demonic. The 3 knocks is ment as an insult to the trinity. Yes, the Conjuring told the truth...lol. Your crown chakra is usually where insight and intution comes from. The intense energetic feeling it that area could be a warning (usually is for me) or the feeling of being highly sensitive to the paranormal going on around you. That's my take on what you described.