sorry it didnt work out for you.. It is really quite hard to eat a proper vegan diet.. and as you may have discovered it isnt for everyone..
This stomach virus is a strange one too.. its had to correlate vegan diet to this, but somehow it may be possible.. You may also not be suited to soya based fermentation products.. who knows! These things do distrupt the normal git flora and change it..
I would recoomend getting a very good probiotic as they really help to normalize the stomach bugs and bring better health.. Then you can keep trying to see what you can eat..
best of luck!