I have suffered dry flaky skin and dermatitis all my life. I've been to many dermatologists, tried all sorts of ointments and creams. Even been prescribed drugs to lower my immune system, to attempt to control the dermatitis.
Never have I been advised to use vitamin B, although I don't think it will do any harm.
Lots of moisturising cream and barrier cream have been advised for me. Also showering with the water as cool as possible and not drying vigorously with a towel, rather wipe the water off, apply moisturiser and then barrier cream to keep the natural oils contained and throughout the day keep applying.
It's not much fun looking like a reptile shedding its skin day in day out.