Hi,
It could be carb flu, but I'm only guessing.
It is more likely to be fluctuating blood sugar levels, you need to be patient with the adjustment to ketosis. You should by now have the knowledge to eat the food you know don't spike you.
You still could have more insulin and insulin resistance to go into ketosis.
But persevere, it will be better for you, if you can get there.
I went through a period before diagnosis when my eyes were blurred consistently, I found it difficult to focus, my opticians were able to see my blood vessels at the back of my eyes were enlarged. My pupils felt scratchy and a minor constant headache behind my eyes. This reversed itself after about a month.
Are you getting enough sleep?