Z.B.
I would stay away from the antibiotics a bit just because you don't want your son getting immuned to them. Have you tried Sambucol/Elderberry - the natural anti-viral stuff? It sounds to me like his immune response is weak and it needs building up. If you do decide to give him antibiotics you can still give him elderberry. I would also give him vitamins C and D3 (or a good multi-vitamin that has them in it). I just read a report out of Japan where scientists studied school age children and the flu. It seems that those children with higher levels of D3 were less likely to get sick than those that had lower levels. Of those with the higher levels who got sick, they were able to "throw off" the cold or flu days earlier. It is just an idea. I would keep pushing the doctors, too, though. There is nothing like a mother's instinct.
Good luck and God bless,
Z.