It may be effectively the same thing as a surgically created (intentional) mucous fistula, even though in this case it's a misbehaving GI tract. At any rate, I'm thinking about what might be causing your nausea. Does the fistula smell bad? Was it making you very upset before (or when) the nausea started? Do you have a fever or any other signs of systemic infection?
A common GI cause of ongoing nausea is gastritis. That's normally treated by significant doses of anti-heartburn medication (e.g. Zantac or Prilosec) for a few weeks. Nausea can be the only sign, but do you happen to have a bellyache?