Why can't I east spicy food anymore?

8 months ago, I could eat all the spicy food I wanted and it didn't affect me at all. Then I went to texas - I ate lots of spicy mexican food everyday and loved it. Towards the end of my 3week holiday I started having tummy pains whenever I felt I needed to go and had to find a toilet quick. I put this down to the quantity of food I was eating. However, since I got back, whenever I eat hot chillis, namely jalepenos, I suffer so bad with cramps and what I can only ume are symptoms of ibs. This never happened until texas and I love spicy food! Can anybody shed light on my situation? Ive eaten spicy food all my life (im 26) and never had a slight twinge until after I went texas. Why all of a sudden?