try the illimination route,
day 1. clear liquids only
day 2&3 clear liquids +Boiled plain rice
day 4&5 as above+boiled chicken
day 6&7 as above+ carrots
continue adding a new veg each day for the next week then add a dairy product, after another week add pork the next week add wheat/pasta continue adding a new food each week until all foods are included again

the reason for doing it so slowly is to make it easy to see which foods upset your system and to give your system time to rest and neutralise itself. as soon as you find one which upsets your system stop including it and wait a few days before including the next new food. it is a bit like weaning a baby, you give one new food then see how their body reacts to it before introducing the next one!!!

if you have diarrhea it could be a bug which you have picked up in this case you need to stay completely off dairy for atleast 4 days as stomach bugs thrive on dairy in the stomach. lactose and wheat intollerances are very well known for causing diarrhea.

domperidone is great for stopping nausea
dioralite is great for replacing the salts lost from diarrhea and sickness
bananas are good for upet tummies too
make sure you are drinking more water than the recommended amounts as you will be loosing more than normal too

thinking of you xx