Hello dear, I am happy that you gave up smoking.your symptoms of cough,yellow flem through nose and headache ,indicates that you are having some sort of inflammation in nasal passages,sinuses or may be pharynx.For this you need to consult an ear-nose-throat(ENT) specialist and it will improve on medication.As you said that after quitting smoking,you re having diffuse body pains,a possible subjective memory loss and lack of sleep,these changes are just a reaction to the abrupt withdrawl from smoking.To get it in a simple way,receptors in your body and brain,which has developed habituation for smoking,has been suddenly devoid of stimulus and the body is reacting accordingly.These changes should settle by time.A psychiatrist s consultation may be taken in this regard.Final word-Don t be anxious,everything will be fine.I hope it helped.