Belle,
the whitish thingy on tongue is normal since she didn't eat much. For the smell, you can use a cloth to wipe the gums/teeth? If pain then leave it till the ulcers go off then see how.
Yalor, HFMD very xinku for young kids. That time RR got it, they were so hungry but couldn't eat/swallow anything, see liao also sad.
When Chloe recovers, bring her out for play and big feast to make up bah. Don't be too sad.