There is a bug going round, mungbeanz - but two weeks is too long, I would get round to the docs if I were. Other answers could be (and I speak from experience) - too much fruit, overripe pineapple, having a bad cold, ibuprofen.
I thought I was dying Sqad! Hospital admittance was discussed at one point :o(. Acquired in Portugal!! the Tom Tits (never heard it called that before either) was the least of the problems - all my joints swelled up!!
Hope you get sorted out mungbeanz. Worth discussing with your GP.
I have had a bad stomach with no other symtoms for 2 weeks before nowtwice (from India, bless em). Both times I had tests and they came back normal. I asked the GP how 2 weeks of diarrhoer can be and she said tha when you shed the contents off your bowel due to infection, you also effectively shed the lining and you grow back a new lining. The new lining is delicate and can get irritated by the food you eat thus the diarrhoer can continue. Two weeks is normally my limit before I get checked out so it it was me, I would give it a bit longer then check it out.