Hurt My Back

I hurt my back somehow this week during my routine. I now have a swollen muscle over my spine just below the small of my back and right above the tailbone. What is this muscle and how did I hurt it. I' ve been working out for months with no back problems whatsoever.
Help.

Have you considered having a doctor look at it?

I' ll have a doc look at it if the pain gets worse but i' m more concerned with finding out what type of exercise may have caused the problem in the first place.

This could happen from a number of different exercises ... squats - deads - military press - back extensions etc. Do you wear a lifting belt when doing heavy lifts? Screwed the small of mine a while back, but have not done it again since starting to wear a lifting belt for exercises that put stress on the lower back.

Actually I was doing bent-over dumbbell tricep extensions when this pain started to occur but what' s weird is that the swollen muscle I can feel doesn' t seem to be one the spinal erector muscles at all. Unfortunately my muscle charts don' t show any other muscles in this area and that' s whay I' m asking for input.

Perhaps you sprained something in the pelvis? I just found this anyway.

Contributions of The Coccyx (Tail Bone).
The coccyx is triangular in shape and attached to the bottom of the sacrum. Its name “coccyx” means cuckoo; it was named because of its resemblance to a cuckoo’s bill—see Walker (1987:253). Because it is not connected to the ribs, the coccyx does not have pedicles, lamina, or spinous processes that are present on certain other vertebrae. The coccygeal vertebrae have only three transverse grooves which provide an attachment to the ventral sacrococcygeal ligaments and the levatores aid, two broad thin muscles which form part of the hammock-like floor of the pelvis. These muscles function as a single sheet which extends across the middle line, forming the principal part of the pelvic diaphragm and support for the rectum. The coccygeus muscle also helps to support the posterior organs of the pelvic floor, especially during blocked forced expiration, as in elimination.

The coccygeus muscle can draw the coccyx ventrally to give added support to the pelvic floor against abdominal pressure. This muscle is inserted by its base into the margin of the coccyx and into the side of the last section of the sacrum. The coccygeus muscle consists of the levator aid and the prirformis which enclose the back part of the outlet of the pelvis.

Brings a whole new meaning to pain in the @$$ huh!

Thanks for all the input. Really learned a lot from the posts and emails. I' ll sure start paying more attention to form and control on all exercises from now on.