She could be going through a leap and going through a milk strike. If so, it should be a passing phase. Hang in there. Babies are smart and won’t starve themselves.
Change the teat to a new size , so that the flow is faster . Observe closely , and try to feed LO just once a day for a start, since LO had diarrhoea.
It happened to my baby before... we let her have milk when shes hungry.. let her do tummy time so that she will be hungy
Might be milk strike. Can try using sippy cup or change your bottle teats to a faster flow.
Probably lost appetite due to diarrhea or recovery from it. Observe longer and see.