The expression is, of course, ambiguous. As a non-committal response to a half-hearted enquiry about our physical, professional or financial condition, it is an effective way of shutting off a pointless, unwelcome discussion.
The other meaning, strictly limited to the physiological and medical, is often evidence of how blind we can be to what is going on inside our body. My gall-stones are, for the moment, my best example. Stories of apparently healthy friends suddenly discovering the presence of inoperable cancer are a far more dramatic instance of the existence of “complaints” we had no way of suspecting.
We can complain about the fragility of the human condition if we like, but should admire people who don’t. Murphy said it best – if anything can go wrong, you can bet your life it will. Realistic resignation does not make bad news any easier to bear. Blaming anybody – except on occasion ourselves – and especially God, makes no sense at all. Self-inflicted complaints, from substance-abuse, for example, are particularly pathetic and too often ignored until it is too late. But even more pathetic perhaps is the blaming of God the Punisher or trusting God the Healer. I cannot say that I have “no complaints” because I will continue to complain about people who preach such rubbish.