Yogi: In certain days, the mind is totally drowned in thoughts, as if it’s the first day of retreat
Sayadaw: When the mind has conditions that settle the mind, the mind will remain settled. When the mind has conditions that unsettle the mind, the mind will start getting unsettled.
Whatever happens in the mind, there are some conditions present that have brought this effect.
It doesn’t happen out of the blue; it’s something that has to do with what has been happening in the mind in the days preceding that. You don’t notice what the mind has been thinking.