What Causes Lethargy And Puffy Face In A Patient With Cardiac Issues?

My daughter is 15 years old with prior cardiac issues (2 open-heart surgeries). She is what the cardiologist viewed in 2014 healthy now. She has been extremely lethargic, tired, moody, pale and a little puffy in appearance in her face for a couple of days now. She had an auxiliary temp of 96.8 yesterday afternoon, and 95.8 this afternoon. She doesn t have an appetite to speak of, nor an apparent desire for liquid. I am concerned I might need to seek medical attention, but am unsure if I should wait until tomorrow to try to get her into her PCP or go on to an ER given the time it is now?