I can only give you advice based on my daughter's hyperemesis 10 years ago. The main concern is dehydration so any fluids she can keep down in the evening is good. If she isn't keeping fluids down at all, she needs to make sure her GP knows this, she may need to be admitted and put on a drip.
Sucking ice lollies can help if her throat is sore from the vomiting and when she starts to feel better remind her to keep up her dentist visits as constant sickness can affect the enamel on her teeth.
I know it is worrying and I don't won't to worry you any more , but one thing I can't stress enough is to keep going back to the GP. The NHS is quite good at dealing with hyperemesis these days but they need to keep being told what is happening.