When you are sick, the blood vessels in your eyes dilate. They want to give oxygen and nutrients to your eyes. That's why your eye aches. In this situation, you need to have a good rest and sleep a lot. Then make sure you drink lots of water to flush out toxins and mucus from your body. But you should not eat much, so your body can use its energy in repairing itself, not digesting. However, if you do feel good enough to eat, eat fruits and vegetables for the nutrients and energy. Besides, try to get some fresh air and some sunlight.