Thank you Darksky
Well I've lived through this evening with no repercussions.
I did what I tell other people not to do and according to the info I could have anything from a cracked rib to cancer.
And that's exactly why we should not be let loose in Google.
At 11pm I was following exercise instructions online to see if it was inflammation and Mr C just thought I was doing yoga.
I'm much calmer now, but when in the street in town I felt very vulnerable and on show.
It could well be muscular, so may either ditch wearing a bra or just not laugh uncontrollably.
Probably my body went in to shock because of not used to laughing and being happy.