Hey Ron thats a terrible experience , dont know what could have caused it but it has happened to me before as well , you feel you need to go and then nothing and then a little while later sharp cramps and you know the rest ,
Before my op I never went out without some padding in my underwear , at least then I had some protection ,
Hope you get over the experience soon and dont let it prevent you getting out and about , sorry I can't give you any explanation but this disease defies explanations in a lot of ways ,