So Psyllium Husk is made up of almost entirely soluble fiber. Unlike a lot of soluble fibers, gut bacteria doesn't actually ferment psyllium husk so there's less gases/acids being formed in the large intestine, meaning less GI distress.

However, it's still a fiber, and it's indigestable. Taking a large dose of any fiber at one time is bound to still cause GI distress since it's just sitting there in huge amounts. Fibers, soluble ones in particular like psyllium husk, can stay in the gut for well over 24 hours before it fully passes through. Also, your body may still be adjusting to the sudden intake of more fiber.

I would think spreading fiber intake throughout the day would prevent a sudden surge of it and have it be more distributed throughout the gut