Up until a year ago I used to have about 4 periods in the year lasting about 6 weeks when I would get colds, flu, viral infections and constant sore throats, within a couple of days starting back I would get run down again, I had sores at the corner of my mouth which wouldn't heal and my skin was very dry. I also used to get eye infections.
This all changed a year ago, I went to see a Japanese doctor here in teh UK and he analysed my diet, he told me to cut out yeast products and cut down on soft fruits and certain vegetables. He said that my diet was actually making me aneamic, he said that most bread/bakery products ahve high incidences of salt which interfere with your body's iron absorbtion. He also said that soft frits such as oranges and kiwis aswell as braed, pasta was giving me an eat and dump scenario when I ate, my stomach couldn't cope with the foods so I would just dump it all very quickly and I would absorb no goodness from the food. He put me ona course of vitamins until I was up to normal levels and then once I was back level he started to reduce them.
In the last year I have had one cold and had the best spell of uninterupted training I can remember. I am a lot more aware of my diet and make sure I eat more hard fruits, nuts and seeds aswell as pulses and a lot of rice.
Maybe you should see a nutritionist