Can't meditate?

I wish to be brief in the matter, a friend recommended this website after a certain meditation struggle. I just did a vipassana retreat, focusing on one's breath, which was done perfectly the first two days. Whenever the mind was distracted I got it back on track. However, I had an odd and pleasant experience during that period, as if a bundle of negativity exploded, and since then not only my meditation became shallow but it were as if my focus wasn't directly on the breath, but on the eyes, as when you see different colors when seeing through the lids. And getting simply back on the breath seems impossible because the mind is entirely focused on my vision, allowing me to perceive the breath but faintly and as if it were in the background of the focus. If anyone had such a hindrance or a way out of it, I'd be most grateful, spending 8days of vipassana not managing to focus properly is a bit of a nightmare. Thank you so much.