5.5month ff DD totally lost her appetite

[EdwardtheEagle]

My DD is taking less than half of what's recommended (only about 80/90 ml x 4or 5) and it's been like this for three days. Doctor said she's fine as she's a good weight and it's not hot at the mo?! Her last two nappies have seemed light.
I'm sure she's teething and have been using gel and a little calpol.
When does it become a problem?

Maybe ask your HV?

I don't suppose there is any cut-off number of days, though - once you get beyond newborn, the overall behaviour and health of the baby is all part of the picture.