What can I eat?
While I can't provide information on what to eat when you have an ulcer, I can provide some general tips. You will want to have a conversation with your physician about an appropriate diet for your medical considerations.
The Academy of Nutrition and Dietetics has a webpage with links on sports nutrition. The link is http://www.eatright.org/public/content.aspx?id=7055.
Another general resource is the USDA Choose My Plate at http://www.choosemyplate.gov/.
Hopefully those will lead you in the right direction.