What is likely hood of 23 year old male, no smoking, no alcohol, don't take nsaids. to develope stomach ulcers ?

Very Possible: 80% of ulcers are caused by an infection with H. Pylori. So, even a person who does not drink or smoke can have an ulcer.

Fairly uncommon: While I can't give you the exact statistics but smoking, alcohol and NSAIDs are big risk factors. And you are are the young side too. Unless you happened to be infected by a common ulcer causing bacteria(H.pylori), a strong family history of ulcers or significant stress, it is unlikely. But to be certain you should address this with your primary care doctor to better assess your symptoms.

Who cares?: I'm thinking you have stomach pain and perhaps believe that knowing if it is or is not an actual ulceration in the tissue makes a difference in what you need to do. It's not very likely, but not impossible. Only a good G.I. work-up will tell. First try to get symptom relief. Anti-acids. No spices, easy to digest small portions. Water before, NOT during eating. CBT Therapy to address your anxieties

Zollinger - ellison: have you been started on a PPI (proton pump inhibitor ) ? example- omeprazole (prilosec ) If so should get relief 1-2 days If poor response refer to gastroenterologist Testing for gastrin levels zollinger- ellison syndrome