HI I have gone through your mail and as you said you have cold for two weeks, and during this period you travel by air,during descend of air craft you feel blockade, popping and cracking of ear. after listening your this story I would like to tell you that there is a tubular connection between pharynx and ear called as Eustachian tube, main function of this tube is to equilise the air pressure of middle ear with external ear.To perform this function this tube opens during act of swallowing and yawing, but when anybody is suffering from cold or sore throat this tube gets occluded due to swelling thus middle ear faces negative pressure which is felt by patient as blockade of ear, this situation becomes more frequent during descend of air craft.To avoid this you should swallow your saliva more frequent during descend of air craft. since you have popping in ear so to treat it you should instill decongestant nasal drops in nose and take steam inhalation.Thanks.