Wa'alaikumassalam! Aiyoh, when babies start with diarrhoea plus cough and loss of appetite, it's best you see the doctor soon okay, could be a few things, and baby needs to be checked properly. A few of my mum friends have been there, and honestly the doc can tell what's going on quite quickly. Just make sure baby is drinking enough, very important when they're having loose stools. Wishing your little one feels better soon!