only things that worked for me:
constantly eating carbs, every 1-2 hours, right up to bed time. Any carbs you can handle, chips, mashed potato, potato waffles, crisps, bagels, ritz biscuits, pop corn, plain rice/pasta......anything! Do not get hungry, ever.
find a drink you like, for me it was apple tango or tonic water. stay as hydrated as possible, sip slowly throughout the day.
don't underestimate the power of rest. rest rest rest rest rest. and if you can't nap, go to bed early (like 8pm!).
take any vitamins BEFORE bed on a relatively full-ish stomach. Never in the morning. I stopped taking vitamins all together cos I just couldn't handle them.
if it's still really bad, go back to your GP.
Hope this helps x