During a recent health MOT, my GP suggested a chest X-ray after noticing ‘crackles’ when I breathed in and out. I am 62, a non-smoker and very active. What could be the cause? Kay Parton, Oxfordshire.

You're going about your day tackling one to-do after the next, when suddenly a strange sound stops you in your tracks. There's something crackling inside of your ear. You give your ear a scratch, but ...