I'm worried about my husband

Poor guy has been vomiting on and off for hours. He gets this about once or twice a year, where he vomits all day and then it finally stops. His doctor thinks it's some kind of migraine, but migraine meds don't help. There's also something called Cyclic Vomiting Syndrome, that I think he might have.

I actually injected him with an anti-nausea med (it was prescribed and the pharmacist showed me how). I'd never injected anyone so that was a bit scary, and then it did nothing even though I'm pretty sure I did it right (I also watched a YouTube video with a nurse showing how to inject into a muscle).

He also takes Gravol suppositories. I'm honestly not sure if anything works but he eventually stops vomiting.

Once we went to hospital after it went on for 10 hours, and they put him on an IV to rehydrate him and give him more nausea meds. He doesn't want to go to hospital but we will have to if this keeps up.

It's so weird, like a "vomit" switch is clicked in his brain and won't turn off, even though he's retching nothing. It takes him several days to recover, and he's been in a bad way mentally lately. He doesn't know anyone except his brother in our new city, and he was learning guitar but had to stop because of tendonitis (for now at least) so he's bored.

I just hope it stops soon.