Thi s is certainly asthma season spring and fall,if the color of the phelgm it may be an infection,green even more of an infection like possibly pneumonia,White or clear phlegm is normal.However if it persists for more than a week i would suggest an xray to rule out pneumonia,Its very common for asthmatics to develop bronchitis or pneumonia.You also can go to the american lung association ,they have many articles on asthma its symptoms and controlling it.etc