I found just eating was good. Little and often. If you can't keep anything down I guess none of these will help, but if you can, here are some random ideas:
Boiled sweets are good because they last and cover that nasty taste in your mouth without filling you up (Tesco does nice pear drops which are a bit acidic/not too cloying).
I found citrus good (chopped up orange).
Protein seemed to fend off the sickness for slightly longer than toast alone: a bit of hard boiled egg, chicken, or cheddar on a piece of toast. For some reason I couldn't stomach butter or marg, so had that otherwise dry.
Grapes were OK.
Crackers... Hmm, that kind of thing anyway.
I went completely off anything creamy, meaty, and most vegetables, but fruit was generally good (pears, plums,...).
Frozen peas or tinned sweetcorn were OK, or raw carrot or courgette, boiled potatoes can work too (though they are horrible to throw up).
Good luck! I know it's awful but it does get better. Lots of sleep is also good: just try to sleep through the worst hours if you can.
LT xx