Might be a tummy-bug. The last time Jude had something like that was when he had a tummy-bug - the time before that though it was Campylobacter. But if your boy is a happy dude, I don't think it would be Campy - that's a nasty bug
The jelly stuff is gross though. Am guessing it is something like the mucous that lines the intestines and passages (as the diarrhoea would be stripping it off the sides?). Just a guess.