Flu/cold/sore throat every month
Since a year or so I am down with a cold/flu or a throat infection almost on a monthly basis. Each time it is the same. Each time it takes about 3-4 days after which I start to feel better.
I visited the doctor about this many times and often I got antibiotics. Usually the story is "your immune system is weak because of insufficient sleep, too much stress, not enough vitamins etc etc".
I have tried everything to improve my immune system: high dosages of vitamines, sports, less stress, more sleep. Yet there is no noticable difference. I still get sick each month.
What can i do? What checkup do i need to get answers? Any help is appreciated!