No. The vitamins will just make your stomach pain worse, if you can even get them down, and if you do you will still puke them back up. But you'll need the water because you'll be puking and shitting out every last drop of fluid in your body for a week or more. Enjoy the ride.
It's not that strong of a withdrawal...I have no stomach pain, either. It's mostly the muscle cramps, fatigue, and anxiety.
Well then, consider yourself extremely lucky. I pray you never have to experience a real opiate/oid withdrawal.
Drinking lots of water and taking vitamins might make you 'healthier' but it's not going to 'ease any pain', if that's literally what you meant - there's no chemical reason for that to happen. It's a good idea to take vitamins in general, and especially when your body is going through shitty withdrawal, and drinking water is good for you - but they don't kill pain, and they won't make your withdrawal noticeably less bad.
you've really just got to wait it out. or ween yourself off, but this is hard for anybody who's addicted to opiates. i just had to sit it out. it sucks but it will be over.
I've never had really bad withdrawls but I'll give you some tips that worked for my friends, that do get it bad, and for me when I get mild withdrawls. Get some OTC codeine from the pharmacy and take liberal doses of that, in combination with alcohol and weed. And lots and lots of water.