To be honest , I’m not sure! The formula is thinner, similar to breast milk, and since she was fine with BM it would seem that the consistency of Neocate would be okay for her too. It think it’s probably unlikely that she’s suddenly developed reflux. Do you thin she been eating more than before,volume wise?
You could as your doctor about thickening the feeds, but I don’t have any specific recommendations for you, I would just be really careful not to use anything that potentially had diary or soy because of her MSPI.