i can feel it too. i get this weight or pressure in my stomach, and it gets harder to breathe. i also get headaches, and i kinda zone out, or become less present in reality, because my mind is elsewhere (probably thinking of si or sui, or the past). i'll be fatigued - for example, even if i get a solid 8 hours i will still feel exhausted, yawning at all times of the day, etc. that's when i know to watch out, it's coming.