My 11 month old has been running a fever for 3 days. Last night I took him to the emergency room with a 103.5 temp. ( what a horrible experience, it took them 25 minutes to medicate him)

I was told that it is just a viral infection and to just wait it out. Earlier today I took him to follow up with his doctor. How told me basically the same thing. His lastest temp was 102.5 at 11am. His doctor also informed me that his wbc was a little low, but he did not seemed concerned. Is it normal for his wbc to be low when it's something viral? I don't know what to do. He hasn't eaten much for the past 3 days, is very weak . I continue to push fluids, I am so afraid of him becoming dehydrated. He has lost weight, 1.5lbs.