The reason I asked is that I had a similar situation with blood in my urine one time and believe there were some similarities to your situation. Several years ago during one of my trips to Ecuador we were traveling in a very hot area of the country. I tend to dehydrate very easily and on this occasion I was dehydrated, additionally we were traveling on some very rough roads being jostled around quite a bit. Later when we made a pit stop, I noticed a fair amount of blood in my urine. I did my best to rehydrate and noticed no future blood in my urine, despite additional travel on rough roads. I think the combination of dehydration and minor physical damage to my kidneys led to the bleeding. Perhaps your situation of being dehydrated and then physical activity was the cause of your temporary bleeding. The other signs sound to me to more like signs and symptoms of early/mild shock (most likely - mild hypovolemic shock) than an intestinal bug.

Pete