I can imagine that having constant hiccups has got to be really disruptive and painful. I hope they've stopped by now, but if not, here's a Mayo Clinic article on it, that says the vagus nerve can be implicated in hiccups. And that persistent hiccups can happen as a symptom of MS. I wonder if going in for that MS angioplasty treatment that pushes on the vagus nerve could help? That would be an expensive treatment though unfortunately.
Here's the link to the Mayo Clinic article:http://www.mayoclinic.org/diseases-conditions/hiccups/basics/causes/con-20031471
Also I wonder about trying acupuncture since branches from the vagus nerve extend into the ear and acupuncture can use treatment points in the ear. That mayo clinic link I sent you (on the page about alternative medicine) says:
When long-term hiccups don't respond to other remedies, alternative treatments, such as hypnosis and acupuncture, may be helpful.
The one thing I do for myself if I start hiccuping that works for me is to stare intently at a point in the distance (like across the room somewhere), with the intention of maintaining my focus on that point without letting my mind wander, and at the same time take a really deep breath and hold it till I have to exhale, and then do the whole thing again, a few times till the hiccups stop. I don't know why that works for me but it does.
Hey, I just went to the page on "Treatments" for hiccups within that Mayo Clinic website link I sent you, and they say:
Surgical and other procedures
If less invasive treatments aren't effective, your doctor may recommend an injection of an anesthetic to block your phrenic nerve to stop hiccups.
Another option is to surgically implant a battery-operated device to deliver mild electrical stimulation to your vagus nerve. This procedure is most commonly used to treat epilepsy, but it has also helped control persistent hiccups.
If you qualify for that implanted vagus nerve stimulator, let us know if it causes any improvements in the rest of your MS symptoms. There is a recent fascinating article in the New York Times about how researchers think that electrically stimulating the vagus nerve may help treat autoimmune diseases. Its not approved for that purpose yet, but I think I read that vagus nerve stimulators are approved in the USA for depression and for epilepsy. Here's a link to the New York Times article called Can the Nervous System be Hacked