I practice Kundalini Yoga since about almost two weeks and after every practice during meditation I experience strong vibrations along all my spine. Maybe not exactly vibration, but sort of like something is "re-arranging". Could it be due to the practice? Can it really be so strong? Thank you.
You should consult your yoga teacher first and foremost. Are you perhaps practicing on your own from a book?
It is certainly possible that these vibrations or energies are due to your yoga practice, although it isn’t usual for most beginning students.
Is it uncomfortable? Discontinue your sitting if the feeling becomes painful, or takes the form of a searing heat, or you are disturbed or anxious.
Assuming it’s not a concern and perhaps may even be pleasant, I would continue your meditation, keeping your focus on your practice and gently guide these feelings / energies upward to the point between the eyebrows.
Generally there is no distinct meaning or interpretation to these phenomena (unless intuitively a meaning is conveyed). Rather it may be that you are becoming aware of subtle energies which, as a consequence of yoga and meditation practices, is both normal and usually a positive, though not necessarily significant, sign.
Gradually acclimatize yourself to these energies and bring them inward to your own center and upward, becoming gradually abosrbed into them. The innate intelligence and consciousness of prana (energy) is self-revealing and generally you will be guided how to respond.
Still, a knowledgeable and intuitive teacher is highly recommended. An inner relationship to God through the form, whether embodied or in Spirit, of a guru is the great treasure on the inner path of meditation.