Hello hong ng,
Welcome to the DhO. Since you're here, as opposed to another dharma forum, you probably already about the Dark Night, also known as the dukkha nyanas or Knowledges of Suffering. Meditation can certainly make life worse before it makes it better. We need to meet suffering face to face before we can liberate ourselves from it.
That said, there is no need for unnecessary suffering.
hong_ng:
have been trying to meditate (by observing the breath) every day. the result is that i develop this not-so-good feeling where i feel that there is a pulse in my head that is very obvious when i quiet down even a bit, and which is too distracting during meditation. a few days back, i was meditating and i felt a great difficulty to breathe normally - i felt like every in-breath the air is entering my head (the upper part) instead of my lungs.
Where are you watching the breath? You might try changing locations if it gets uncomfortable. If you get tension in your head it might be from too tightly watching the breath at the nostrils. Try to relax your focus a little and don't worry if you can't always feel the breath. Move your attention to other areas of the body, such as the belly and watch the breath there. You might also try watching how the breath affects the shoulders, and particularly the back - there is a lot of lung space behind us, so try breathing into the shoulder blades, and the lower back. Feel the muscles in the lower back expanding and widening as you breathe.
Get yourself a soft 9 inch Pilates ball (a few pounds/dollars/euros on Amazon and elsewhere) and lie down on the floor with the ball in the bones at the back of the skull (not the nape of the neck). Now, with your nose, make very very small, very slow circles - the size of a coin. Do this for a few minutes, then switch and rotate the other way. This helps relieve tension in the skull. You can also try focusing on the palms of your hands - for some reason this can help release tension.
I would really recommend checking your posture with someone else - a yoga teacher, meditation teacher, physiotherapist, Qi Gong teacher or an Alexander Technique teacher. Do stretches before you sit:
here are some for the lotus posture that can be used for all sitting postures. I also have found some good stuff on this site:
saveyourself.caOnce you've done all of that, you may still find the tension is still there. I have experienced something very similar in meditation and it was, as you say, terrifying. It wrecked a ten day retreat that I did last year, and then cropped up again in the middle of a two week retreat I was on in April. The second time, I made a resolution to treat it with the utmost patience. I was doing walking meditation, focusing on the feet as much as possible, but stopping and coming to a standstill whenever the tension intervened. Then I would note - very patiently, and very gently - the tension, the aversion, the fear and - most importantly - the "story-telling" that was going on. I had been telling myself all sorts of horror stories about what the tension could be, and coming up with all sorts of schemes to get rid of it once I was off retreat. None of this was helpful - it just exacerbated the problem. Meeting the tension gently, patiently, with kindness, and yet more patience, was what allowed it to relax and soften eventually. Try doing that - particularly while walking, since this will get around the breathing and posture problems.
Good luck,
Andy