If you lift a lot (and not properly) and also lift heavy weights while working out, that might affect you having this back pain. Back pain is such a common ailment for people, even in the generally healthy and sometimes young, because unfortunately, our anatomy puts a lot of pressure and stress on our spine due to the fact that we walk on 2's versus walking on 4's. Animals that walk on 4's have their weight evenly distributed in more areas, but being that we walk upright, we have a lot of pressure on some of those joints and disks. The reason I bring this up is just to remind that that back pain is common.
Also, if your back suddenly became painful in a moment while you were bending over to put on a sock, this would also point to the fact that your pain is probably due to a pulled muscle connected to your back or a temporary alignment issue. (I think)
Usually that sort of pain goes away. Something happened to me like that a few years ago, and I was in a lot of pain for a few days, but luckily it went away within a week or so. I imagine you will probably have a similar story... but keep in mind even if it didn't go away fast, it still doesn't mean its serious, you may just have to be careful about how you lift and move for a while.
Hope you are feeling better soon!