Hello OP!
Hopefully I can provide a bit of advice and reassurance here, I suffered with severe hyperemesis from 5 weeks onwards and was in hospital for 6 months straight.
Firstly, don't worry about vitamins etc. Babies are little parasites and will take what they need from you (even the nutrients inside your bones with go to them) so make sure vitamins are the least of your worries. Don't even bother with them if they make you sick
Secondly, cyclizine is notoriously crap and actually doing anything to help sickness. The only reason the doctors give it to you first is because it is the cheapest anti sickness drug you can get on the NHS. Works for a few, but for a majority it really is no good.
There are multiple other anti sickness drugs- metoclopromide, phenergan, and the God of anti sickness is ondansetron.
However, you make find if your sickness is very severe (like mine was) that taking these in either tablet or liquid form had absolutely no effect, or you just sick them back up. So somethings metoclopromide works well as an injection- doesn't necessarily stop the sickness well, but it does make you sleep so you get to kip for a few hours.
Phenergen also knocks you out.
Ondansetron is brilliant through an IV drip.
You may find, as I did, you need all of these drugs in combination to get a good benefit.
Some doctors are careful about which drugs they prescribe as previously there have been some inaccurate testing that said they harm the baby- please be reassured that present testing and studies have shown they cause no harm.
Please go to hospital if over the course of 24
Hours you haven't kept anything down to hydrate you- the hospital won't necessarily be concerned you haven't eaten, but dehydration is a concern.
You may find a drip of fluids gets you up and going again.
Do not be afraid of going into hospital daily to get a drip.
And do not be fobbed off by anyone who says it is morning sickness.
You may have to put your foot down to be treated properly.
I hope that helps but any questions please ask!