back pain cause

[Wynton]

Yesterday, while playing tennis, I developed a new back pain. Though I occasionally pull a muscle in the upper, middle part of the back, underneath the shoulder blades, this pain is in a different location and doesn't feel like the type of pulled muscle I am familiar with.

Specifically, I feel strain in the very lower part of the back, from the tailbone and up a few inches, and not centralized to a particular spot. Its fairly stiff and uncomfortable when I lay down totally flat (though not when I sit).

So I'm wondering how this might be diagnosed. While I know this pain began while playing tennis, I don't remember it starting with any particular trauma or action, which I would associate with a pulled or sprained muscle. And I'm not even sure if there are muscles in that region of the back. I don't think it's a slipped disc, because I would have thought that would be accompanied by more acute pain. This is more generalized.

Anyone here experience something similarly? Are there particular stretches that help this? Since yesterday, I've been applying heat (which has helped my back in the past) and using anti-inflammatories, but the condition is unchanged.