We see this fairly often, a person goes through an intense spiritual or transcendent experience, and afterwards they begin having some very strange things happen to them. They may start having sensations of intense heat or energy flowing through their body. They may start hearing tones, often very high-pitched. Their body may begin to feel like it's vibrating, or they may feel pressure in their forehead. It's common for people to believe they're going insane or even dying when this stuff starts to happen, but don't worry, all this is actually quite normal for a being who has chosen to raise their Consciousness, and it's called Kundalini activation.
Now the term Kundalini itself is tied up with the various Hindu religions and also a number of Western mystery schools. As such, there's a lot of conflicting beliefs about Kundalini and a lot of people who will tell you the "right" and "wrong" ways of going about it. I'm going to steer clear of all that stuff as much as possible, and simply share what I can confirm from my own experiences.
The first thing to understand is how the chakras work. There are seven main chakras that are aligned with your spine. One at the very base of your spine (root chakra), one a little below your belly button (sacral chakra), one a little above your belly button (solar plexus chakra), one in the center of your chest (heart chakra), one in your throat (throat chakra), one in your forehead (ajna chakra or 3rd eye), and one at the very top of your head (crown chakra). Each chakra corresponds to something different, for example the throat chakra has to do with communication, among other things. There's a number of websites that do an excellent job explaining which chakra corresponds to what so I wont bother going into detail here (here's one such website: http://www.poeticmind.co.uk/wellbeing/chakras-and-dantien/ ).
