May I know what causes this bumpy redness on his chin?

Most likely milk rash, it’s not an allergy or something so you don’t have to change the milk however after every feeding be sure to wipe his mouth frequently with damp cloth. It will be better if you can clear the milk thrush in the mouth too as it affect baby oral health ☺️ don’t worry too much most baby has it at one point of time!

Most likely milk rash mummy! Not because of u choosing the wrong milk but babies sometimes will have some milk spilling around their chin hence theres this red bumbs.. my son do have it too but constantly wipe their chin properly, put some cream and its gonna be fine! ☺️☺️☺️

if there’s ulcer in the mouth then it can be the beginning of hfmd, just keep a lookout mummy

Use wet cloth to wipe after milk.

milk rash?