Inflamed gallbladder. Hida scan shows 29%. No gallstones. Symptoms are not severe, minor back pain, nausea, elevated pancreas levels (301), acid reflux. Any other option besides surgery? If so, what?

Surgery not. An option, you symptoms are ' not severe' , no evidenced sepsis , cholecystitis with out stones will subside with time , no need for surgery , get your relax treated with medications , speak to your doctor.
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Spasm. My understanding is that there is no visualization of the gall bladder when it's inflamed. Sometimes sludge in the gall bladder without stones or spasm of the gall bladder sphincter can produce symptoms similar to gall stones. I would consult a general surgeon to analyze your symptoms.