For reasons he can’t explain, he started excessively washing his hands.
...
in Knight’s brain clicked, and he began to have thoughts of contracting diseases and getting sick.
These two parts stood out to me.
I have OCD, and I have been through exactly what is described here. It's terrifying. OCD is not like it is portrayed when joking with your friends about wanting your pencils parallel with the edge of your desk. It is a debilitating disorder that prevents you from living a normal life.
For me, the "click" moment was also when I was in college. As a sidenote, I think the fact that this manifests in college for a lot of people is not a coincidence. I think the high stress of college is a huge contributing factor (Obligatory not a doctor. Just a pattern I have observed.). Anyway, back to the story. So I was taking a piano class in college as a fun, personal-enrichment, filler class. I took the class at night time. It was the last thing I did before driving home and going to bed. The pianos were visibly dirty. Like grime caked on. So I would always just think to myself that I should wash my hands before I go to bed, because I touch my face a lot when I'm in bed. Then one time I touched my phone and I thought, "oh I should.clean my phone before bed, because I touch that in bed and then touch my face." And then I once touched my elbow to the piano and thought the same thing. And then I started thinking that every time I touched a door handle. Or sat on a chair. Or brushed up against a wall. Suddenly the world was filthy and every time I touched anything, I immediately had to clean myself. Over the next year, I spiraled HARD. It got to the point where I couldn't open doors. I would get trapped places and need to wait for someone to open the door for me. Eventually I started seeing therapy because that obviously wasn't a sustainable lifestyle. That helped me soooo much. I can have a normal life now. I still have a few weird quirks, but I can live with those.