My baby also initially improved on HF however after 2/3 weeks all symptoms returned as she was having a build ip reaction. We ended up on SMA Alfamino
That happened to my baby too. He improved the first week and then he went back again. After 6-8 weeks he was fine again and completely settled. It can take around 6 weeks so I would wait a little bit more. My baby ended up on Alfamino because his eczema never disappeared completely but the rest of the symptoms improved so much with Aptamil Pepti x
Definitely possible! My baby improved initially on hydrolysed formula, but then some symptoms returned and she's now on amino acid formula 😑