Hi, so sorry to hear you're suffering. I am pg with my second baby and have had hyperemesis this time as well as last. With the first it was bad for 18 weeks (in hospital quite a lot, on a drip, scary drugs etc) then it went away almost, only to return at about 28 weeks for a month or so. This time round I have been worse to start off with, i.e. more sick and "ill" iykwim, more hospital admissions etc but again at 18 weeks it seems to be clearing. Doctors have said that they can't tell whether it will hang around like last time or if it will go away completely. So guess what I'm saying is there are no hard & fast rules!
The website that singsong linked to is excellent, some really good remedies on there (the one that has really helped me is drinking cold drinks- sugary squash with lots and lots of ice actually settles better than anything)
Also I have found that indegestion triggers my vomit-fests so perhaps steer clear of any food that makes your digestion even vaguely dodgy, and only eat tiny tiny amounts at a time. I mean tiny. Like half a potato an hour. No fun when you have two stomachs, one saying "Feeeeed me fgs I want food NOW!" and another saying "Don't you even dare think about eating. Oh god I'm gonna throw up..."
Its really important to keep your fluids up even if you can't manage food, if you start getting dehydrated your bod produces those lovely things called ketones (basically your body breaking down its own fat reserves) and ketones make you feel sick. SO you vomit more and you get more dehydrated and then you produce more ketoes...you get my drift So if nothing else keep drinking!
Also if you find you are puking the tablets up ask your dr if you can get other types- suppositories for up yer bum or meltlets, which dissolve on your tongue so you don't have to swallow them for them to work.
Sorry for monster post- really feel for you though. I hope things improve soon- hang on in there it does get better honest!
xxx