What should I do? Please help?

For the past few days a little bellow my belly button has been hurting. 2 nights ago I had the worst of it, it hurt so bad I couldn't do anything. The pain has its highest points and its lowest points. My dad told me he had stomach pain at the same age as I'm currently. (He has ulcers) I'm not sure what to do. I currently can't sleep because of this throbbing pain. I haven't changed my diet either so I don't really think that's the cause though it may be. Please give me tips or any kind of help. This is starting to worry me, thanks