Grade: 3
Nasty back pain, all down my left side. I used to suffer from it a lot. Happened suddenly as I got out of bed, having been in it for a long time. Couldn't really move let alone walk/run for the rest of the day, however by the evening I was able to go to a party, and by the following morning, I was able to run gingerly (using an Ibuprofen as a precaution.)
Caused I think by lying in the soft chalet bed for 12 hours straight (as I was feeling ill from the night before.)