Need a break. Potentially, you are also working out too hard - plus, you may find it useful to change your reps and set numbers in an undulating pattern to encourage better muscle response than to keep to a consistent pattern.
If you workout in a common gym area, you may be re-exposed to a common virus that is 'going around' in your area . Keep your own spray can of Lysol and a pile of cheap rags that can be used to wipe down equipment (or, if you lucky like I am, you belong to a gym with a large and clean supply at hand for this purpose) before and after use. Learn to keep your hands away from your face/nose/mouth eyes to avoid cold and flu virus contamination. Wash your hands frequently during the day, learn to avoid directly touching common sufaces (door handles) in work and public places.
Boost your immune competence by eating plenty of fresh fruits and vegetables, grains (brans, oats and barley), and root vegetable fiber. This is your key to better health. Beyond improving bang for buck in your dietary absorption efficiency, it will also help keep your immune system properly regulated (eg., low allergy, high microbial attack status) during the cold and flu season. The latter included fewer secondary infections (post viral attack,like bronchitis, bacterial pneumonia, sore throats, sinus infections, strep, etc).
