What could cause recurrent sore throat, congestion, drainage, coughing, and fever 101 or higher?

My three year old daughter has been getting sick at least once a month or every three weeks with recurrent sore throat, congestion, runny nose, coughing, and fever that ranges from 101 or higher. We have had lab work each time and everytime her white count goes up high. Dr puts her on antibiotics and then it goes back down. We finish antibiotics,, she gets better/well.. life goes on and a few weeks later, she's sick again. The dr has done lab work to check her immune system for deficiencies and it came back fine. It's been abot a little over a week since she finished her antibiotics this go around and shes getting a sore throat again and is hoarse, congested and coughing. It looks like we are about to be sick again. SIGH Anyway, she's missed so much pre-school because she can't stay well long enough. She just went back this week (twice), and here we are apparently getting sick again. Her dr is sending her to an ENT since her symptoms are always the sore throat, congestion, etc to see if we can get some answers there, but they couldn't get her in until September! UGH. I am a mom whose desperate to find some answers! Has anybody else heard of a young child getting reoccuring sore throat, congestion, fevers, etc? Any ideas what this might be?