I have been meditating for 3 years now and practice Hatha yoga on a daily basis. Just last year I activated my ajna chakra (spiritual eye) and ever since then the pressure there has been increasing, so much that I feel a heat from there spreading over my eyes. At times it makes me feel and look dull. So I was advised to delve into sun-gazing, and to meditate on my crown chakra, which I think has lead to heat on my head as well. A tickling pressure and heat.
—Ibrahim Clouds, Nigeria
The sense of pressure between the eyebrows, and warmth, or even heat, is quite normal. It is simply a sign that energy is arriving there, nothing more and nothing less. That energy can be experienced in many ways, for example as cold, heat, pressure, tingling, an energetic movement going here and there. Sometimes it even gives a sensation of headache, which it isn’t (just the body is getting used to it).
Make sure you remain very relaxed, whatever you feel. Relax the forehead. Relax your mind. Emphasize relaxation, enjoyment, not intensity of concentration, for now.
You feel the energy spreading over your eyes. Good. But what seems odd is that it makes you feel dull, and this is what makes me wonder a little. The very opposite should happen. Energy at the spiritual eye stimulates superconsciousness, which is the opposite of dullness. Where is that dullness coming from? How can energy there be dull? Is it because it is too much? Is something shutting down?
Try instead to intuitively feel the very high, luminous, and awake state of consciousness which is situated between the eyebrows. It is Christ Consciousness. It is the seat of ecstasy in the body.
About sun-gazing: the sun is indeed a symbol for the spiritual eye. It is a generally a good practice when done at sunrise or sunset, but not when the sun is high. It stimulates wisdom. But I don’t know if it’s a good practice in your case: it will increase the sense of heat, instead of diminishing it. It is not relaxing, but stimulating. See for yourself if it helps you or not.
About meditating on the crown chakra: Yogananda didn’t advise to do so. So I’d not continue. I know that the sense of pressure and heat can be felt on top of the head too, but it isn’t something to stimulate consciously.
I am glad that you practice Hatha Yoga. When the inner energy rises as in your case, we need the earth element, and working with the body will give you a good grounding. Even sports would be good.
In short, if you want a suggestion: try to get away from that sense of dullness. If the energy is too strong at the spiritual eye, for now you may concentrate on the heart chakra in your meditations, emphasizing devotion. But leave the crown chakra alone.
All the best, inwardly,