Hi, I once ran a 20 mile race fairly hard but enjoyed every minute of it and thought I'd rehydrated well throughout the race. Shortly after finishing I ate a huge roast dinner with plenty of vino, but this is nothing new for me after a race. However, the following 3 days were a nightmare with stomach cramps and chronic diarreah (sp). Everything I ingested came out the other end immediately, although I felt perfectly well in myself.
I put it down to my body being over-exerted (not a bad thing) and completely thrown out of synch. AFter 3-4 days I'd had enough and took some Immodium which sorted the problem immediately. I have since run other races and not suffered the same problem but I am aware it may happen again.
Put it down to experience and be ready with the Immodium next time. 