Hello and welcome to HCM! I understand your concerns very well. Having cough with yellowish or greenish mucus suggests for a complicated brochitis, an infection of your lower respiratory tract. Have you high temperature? You have been a smoker too, that means a higher risk for this medical condition. You have to take a combined cure with antibiotic and expectorant. I d suggest you azithromycin or clarithromycin combined with bromhexine for the mucous. Vitamin C would help to increase your immunity strength. Drink plenty of juices since it helps recover fast. Take care and all the best for you! Dr Eriol.