Thanks guys.
Bob, one of the 'three' doctors I saw said she had been ill with it and off for 5 weeks earlier in the year, despite having the flu *** in November. She said it was probably a different strain that the *** didn't cover.
I've never heard of it lasting for so long, I hope it's not a sign of things to come. On the upside, my asthma medication has been closely scrutinised and is now the best it's ever been.