Hay, mama, ang oral thrush talaga yan frustrating, one of my mum friends had the same issue with her son for months, and they finally got it under control with the pedia's antifungal medicine plus being super strict about cleaning lahat ng toys, bottles, pacifiers with hot water regularly kasi nakakabalik siya if hindi thorough. Since it's babalik-balik na talaga despite treatment, I'd really suggest asking your pedia for a second opinion or maybe go to a pediatric dentist, baka may something else going on or the thrush is getting reinfected from somewhere, especially if mahina sya uminom ng water kasi that can make it harder to clear. The water intake is important pero don't stress too much about forcing it; ang main thing is getting to the bottom why hindi talaga naalis, and a specialist check might give you better answers than what you've tried so far! Sending you hugs, FTM, alam ko ang draining ng repeated visits.