Hi montrealhomegrown.
Stomach ulcers are a different ball game. Are you sure you have them?
If so, the best treatment is with raw cabbage juice.
After several weeks on that regimen, including a raw organic diet (hopefully) they should be healed.
Only then would I contemplate a Water Fast to rid the body of candida.
Of course it would be possible to fast with stomach ulcers with the intention of healing them, but I would strongly advise a supervised fast by an experienced and qualified practitioner in fasting if that is your preferred choice.