Hi Jason,
The first meditation I undertook was untrained and came from Sogyal Rinpoche's 'The Tibetan Book of Living and Dying'. It was a practice called Tonglen or 'Sending and Receiving'which consisted of breathing in and out, on the in-breath taking in the suffering of the world and on the out-breath sending out peace to all who suffer.
The results, within 20 minutes, were surprising: I experienced an energy coursing through my body and especially in my spine. It felt very overwhelming. I stopped and then tried the practice again to see if the result could be reproduced (born scientist

). It could but it was not an outcome described in the book so I stopped it there. It was not unpleasant but my guess was that on some level my approach to the practice was faulted, probably due to a lack of grounding in meditation. I am not a new-age type but for want of a better word I would say this was a manifestation of kundalini or life-force, magnified or concentrated by the way I did that practice.
It's easy and seductive to get drawn to reproducing such manifestations or be put off practice by them.
You mention being taught Anapana at the nostrils. This is probably something that comes from a mistranslation of the Pali word Paramukham, which could be read as 'around the face', literally in the sense of physically around the face, or could be read as 'to fully face', as in to be fully mindful of. The second makes better sense of the meditation sutras. It's also in line with what the Buddha actually taught:
Breathing in long, he discerns, 'I am breathing in long'; or breathing out long, he discerns, 'I am breathing out long.' Or breathing in short, he discerns, 'I am breathing in short'; or breathing out short, he discerns, 'I am breathing out short.' He trains himself, I will breathe in sensitive to the entire body.' He trains himself, I will breathe out sensitive to the entire body.' He trains himself, 'I will breathe in calming bodily fabrication.' He trains himself, 'I will breathe out calming bodily fabrication.' Just as a skilled turner or his apprentice, when making a long turn, discerns, 'I am making a long turn,' or when making a short turn discerns, 'I am making a short turn'; in the same way the monk, when breathing in long, discerns, 'I am breathing in long'; or breathing out long, he discerns, 'I am breathing out long' ... He trains himself, 'I will breathe in calming bodily fabrication.' He trains himself, 'I will breathe out calming bodily fabrication.'
Maybe rather than trying to learn about this particular manifestation of energy you are experiencing, which I note you find troublesome, you could experiment with practising the way the Buddha taught to gain the proper grounding.
The instruction above includes two specifics: 'breathing .. sensitive to the entire body', not your nose, toes or belly, but the whole body, not any conceptualised idea of the body, but the actual physical sensations; and 'calming bodily fabrications' which invites you to be indifferent to the phenomena you've experienced and let it go, calm it.
Many people have discovered that trying this works better for them as a starting point for mindfulness meditation. It might be something you would benefit from. It grounds you in the experience of the body, calms body and mind and develops concentration without being too tight.
Something about the way you are practising now is unbalanced leading to this experience and difficulty meditating. Time to ride another way, I'd suggest.
Kindly,
Matthew
PS from the homepage there is a link to an article on Shamatha/calm abiding mediation that starts from this and gives more detail, how to deal with thoughts, etc.