Thanks. It was probably a post-op complication of a gall bladder op that had to convert to open hence lots of post-op pain, probably not enough pain relief and severely restricted breathing - there is no underlying pathology.
Guess I'll have to be patient.
And since I fly a single-seater, taking a doctor that could reinsert a drain is bit tricky! (it was also 'uncomfortable' in nurse speak and not something I want to repeat)