This kind of pain doesn't sound as much like ibs as it would for something like GERD or gastric/duodenal ulcer. Ulcers usually can be treated with acid inhibitors and/or antacids. If they're caused by H. pylori, antibiotics can get rid of them. If its that annoying, and especially since you described it as burning and gnawing, leads me to believe it's an ulcer...specifically a duodenal ulcer, since you said it's right around your navel, instead of the usual pain above the navel with gastric ulcers. But this is just assuming it's an ulcer at all. Better to just go get it checked out.