In my own experience, if something is painful there is generally a good reason.
After only running W1R1, my knee started hurting, almost 2 weeks later, not much better.
No use going to see my GP, as I know I would be told to take pain killers and anti-inflammatory tablets and maybe given a Cortisone injection, hence a visit to my Chiropractor. Initially she thought it was from my SI joint but I was still in pain and went back today and it is definitely a knee injury.
So I am sat here with strapping on my leg, from below knee to high up on my thigh, quite tight to keep it straight, which enables me to be able to walk on it without pain and have to go back Friday.
While there must be many people on here who have had various injuries and recovered fully, it is still worth getting checked out, long term injury is not good.
On a brighter side, it is still great reading how well everybody is doing and also how others encourage people who are struggling just at the moment, keep running safely and be proud when you do.