I am 18 years old, in college, have a job, and keep myself very clean and constantly have my hands clean. I get sick maybe once or twice a year, but usually not at all. This year I have had a cold at least once a month and last week I felt this baseball sized knot in my stomach causing me to constantly feel like vomiting and constantly needing to go to the restroom. It has gone away by now, but my stools still have not harden. I noticed a white-ish worm with red rings about four, maybe five inches long in my stools recently after the pain has subsided. What are these worm like things and why am I seeing them?