Runners can explain most of their injuries. They either trained too hard, didn’t stretch, wore the wrong socks or shoes, tripped and fell, or had some other specific event happen to cause an injury. But I’m guessing that most runners have also gotten an injury they can’t explain. That happened to me again a few weeks ago. I didn’t change any part of my training but one day about two miles into an easy four mile run my hip started to ache. I tried to run through it but after a minute I had to stop and walk because the pain was too great. I walked for a couple of minutes then gingerly jogged and walked a direct shortcut home. The next couple of days my hip hurt when I walked so I took time off running. I skipped four days of running and most of the pain was gone when I walked. With a half-marathon coming up in a couple of weeks I decided to play it safe and took an extra two days off. Then I cautiously got back to training but eased up on the mileage. After a week of reduced mileage I felt fine and increased the mileage again without problems.
Random injuries will happen. We can’t control that. But we can control how we respond to them. Years ago I would tend to ignore them and keep running. Depending on the injury, I could occasionally get away with that as a young runner. But now as a more “mature” runner I have learned that being cautious will get me back on track faster. It’s not always easy to sit out for a while but missing a few days is better than missing weeks or a season or worse.