Orange tree has been bearing orages for 10 or more years. Leaves that have dark spots are discolored yellow and green. Bottom of leaves has slightly raised dark sploches of various sizes from pin points to 3mm donut shaped. The spots are a medium greenish brown color. I can email a photo if given an email address. I am trying to determine if tree needs some care and what that care would be to relieve this condition. Not all leaves have this discoloration on their bottom.