Here's a layman's opinion. I think 6 miles is definitely distance training. Most people would fall over after running 1 mile. 6 miles is REALLY hard work.
two; running is one of the most stressful forms of exercise there is. When your body is stressed, it goes into EVACUATE mode. and so your body does that; your intestines want to empty and if you really get going, you're going to vomit because you're carrying extra weight in that full stomach. Those are responses that echo the deep deep past of our genetic programming.
Having said that; go to the doctor. i don't like the sound of this blood stuff.
Urgent care is great; but now go to an Internist and get more than symptoms treated. good luck.