Haven't slept well in a few weeks, a crackling sound in lung when breathing and mucus in throat with dry cough, gets worse after I eat, lung cancer?

Respiratory illness. It definitely sounds like you have a respiratory illness with sputum production. If you have fevers, you should definitely go in to see the doctor.Flu season is starting to arrive and it is a good time to get a flu shot and have this issue addressed by visiting your physician. Good luck.