Could a form of gallbladder disease cause abdominal pain, fatigue, and being lightheaded. also could it cause alt enzyme levels to be mildly elevated?

Yes, but so could...: ...lot's of things that inflame liver cells, as is indicated by elevation in serum transaminases (ast and/or alt). Hepatitis can be caused by a variety of issues (infectious, ischemic, metabolic, toxic, infiltrative, alcohol-related, drugs, etc.). You could even have mononucleosis. So what tests have been done & what has been ruled out?

No: Gallbladder disease is often associated with fatty food intolerance. It usually causes pain in the RUQ after eating with nausea and sometimes vomiting. Elevated liver enzymes is not associated with gallbladder disease unless you are passing a stone where the elevation is temporary. Persistent elevation in ALT is due to either medication or fatty infiltration of the liver. Biopsy may be needed.