I just bought a horse with similar symptoms- he's very girthy and sensitive to the touch in his girth area, especially so on the right side. He also cribs a lot, which can also be caused/made worse by ulcers.
My vet recommended starting him on U-gard, since an endoscopy is very pricey, as are the drugs to treat ulcers (UlcerGard or GastroGard). Since I'd probably try treating him with something cheaper to begin with, it seemed to make sense in his case to spend $25 on a bucket of U-gard and see if that helps before going forward with more expensive diagnostics & treatments.
I've also heard very good things about aloe vera juice, so I might see if I can find a big bottle of that somewhere and add a couple ounces to his feed each night.