causes of recurrent strep in four year old?

My son is four and has had strep 5 times since September(in addition to ear infections and pinkeye) and has alternated medicine each time to avoid building up a resistance.  He recently had strep and finished his antibiotic. Within the week he was back on an antibiotic and this week he still has a fever, achy bones, lethargic, stomach pain, swollen glands, and white spots in his throat. The chest x-ray and mono came back negative. I'm wondering if anyone has any ideas as to why he keeps getting so sick. We get rid of his toothbrush and his hygiene is not an issue. As of today he will have been on 10 days antibiotic (with only 6 days off previously) and now has been prescribed for another 10 days. He will be going to an ENT in two weeks but Iam really concerned, please help with any information.

[OHNS2010]

Hi, this happens to be a common problem with some children. They will be having persistent cold in spite of the best antibiotics. I would like to suggest few things for you:
1. It could be chronic adenoiditis, leading to persistent fever, cold, nasal block and  
    ear complaints.
2. It could be rheumatic fever as you have mentioned that there is persistent fever with joint
    pains.
3. White spots in the throat could also be due to dehydration.

So things to be done are:
1. Get the following investigations done- C-Reactive Proteins, Complete blood count, X-ray
    lateral view of nasopharynx (Schuller's view) to look for adenoid hypertrophy and
    impedance audiometry (to look for fluid inside the middle ear).
2. Get a culture sensitivity done for the throat swab

[irishgirl77]

Thank you very much for your help, I will definetly follow up with your suggestions:)