I know they do go through reduced appetite at that age. Has she dropped in percentile, or has she always been 5% in weight?
I wouldn't reduce milk intake if it is all she will take, I'd think she needs the calories, certainly she needs the fluids. If she is still bothered from the virus or her molars, what about making the foods really smooth and bland, like offering purees (stage 2 type)? And focusing on really high-cal foods, like whole-milk yogurt, avocado, cheese, or sweet/tempting foods like banana, sweet potato, etc.
That's all I can think of off the top of my head.