Gall bladder surgery while pregnant?

Tuesday, I went to the ER with severe pains that wrapped around to my back, and vomiting. Afraid of preterm labor, I went to the closest hospital that has an OB ward. The ER de gave me milk of magnesium (didn't hook me to any monitors or anything) and told me he thought it was acid reflux, and sent me home, with instructions to follow up with my OB. The next day, I was still in pain, but not the razor sharp pain it originally was, more of an ache. Went to my OB and she didn't even know I went to the ER (apparently they hadn't put it into my file), and was very upset that they didn't do an ultrasound of my gall bladder. I'm under strict orders to avoid anything fatty, or anything with a whole lot of sugar. Nothing fried. And an ultrasound is set up for this week. My OB is under the impression that my gall bladder might have to come out, while I'm pregnant. 
Anyone hear of this? Have it done? I'm scared.