My Husband Has Been Having Pain In His Stomach Earlier

My husband has been having pain in his stomach earlier in the day and then as the day gets later and he eats, then the pain moves more down into his intestines. We were wondering what the systems were for an ulcer and what causes them. He did have a kidney stone that he passed about four weeks ago and he was wondering if maybe this was the start of another one. We were also wondering if he could be a urinary tract infection. He doesn't have any other symptoms other than the uncomfortable and sometimes painful feeling I mentioned above. Thanks much for your help!