Hi Helen, I'm 12 weeks and am on my 2nd HG pregnancy, I think I must be nuts for putting myself through it again!
I'm on cyclizine after trying a few other medications. Did they manage to get it under control in hospital with injecting the antiemetics, and did you feel better before they let you out? Possibly you may benefit from the antiemetics that dissolve under you're Tongue or suppositories. The antiemetics do really make a difference if they're taken regularly and for a period of time. I was admitted a week or so ago in quite a bad state, but since then I've taken the meds religiously and now I just feel ill instead of the 'i'm going to die' feeling.
Are you going to the docs regularly to keep an eye on you're ketones. They should be suggesting this to you, don't put up with shitty care for HG.
The only other things that made me feel a bit better was full sugar coke and crisps. Tbh this was like a piss in the ocean for any type of relief, but you take what you're given 
I know how you're feeling, am still pretty rough myself, but it DOES end. I realise it probably doesn't feel like it while you're feeling so ill, but it will.
Let us know how you're doing x