Aiyoh, I totally feel you, so stressful when baby reject everything and you dunno why! My youngest also went through a phase around that age where she reject her usual milk and kept having loose stools, turned out the diarrhea itself caused what my paed called secondary lactose intolerance, meaning the tummy lining got irritated and cannot process lactose properly for a while. Someone in my mum WhatsApp group mentioned her paed also recommended lactose free or Isomil for about 2-3 weeks just to let the gut recover, and after that slowly wean back to normal formula, so maybe give it a little more time lah, the tummy needs to heal first before it can accept anything properly. My neighbour brought her baby to KKH when her LO kept rejecting everything including water, and the doctor there told her the rejecting and diarrhea together can sometimes mean the gut is just very inflamed and uncomfortable, so baby associate feeding with pain and then reject even more. One mummy in my group also tried many many brands, S26, Enfagrow, Isomil, Snow, and said sometimes you just gotta be patient and keep trying small small amounts so baby don't feel so overwhelmed. The most important thing now is to watch for signs of dehydration ya, my friend's baby got hospitalised because of that, so if LO is not having wet diapers or seems very lethargic, please don't wait. Do check back with your paed or see a specialist to get more personalised advice for your LO's exact situation, hope baby recovers very soon, jia you mummy!