In fact, I am researching on this question as well, but I may have a possible cause. About two months ago in a high school football game, I jumped up and landed completely flat on my back on the artificial playing surface. Although I had a back pad, I experienced this "fluid filled swelling," and still have days with alot of swelling. One possible cause of this could be from a rupture of the protective coat that surrounds the muscles that surround your spine. If anyone has any more detailed explanations or a different one I would be happy to read your posts.
Obviously there are many cases that can lead to lower Back pain- I read a passage recently about excersizes you can stop doing. One of them was sit-ups. It said they don't do much to flatten your tummy and can make your lower back kill!
If you want to read the passage click the link below (or copy and paste into the web address box). Then click the arrow to the right to look at the next picture. Another internet window will open with a picture and a passage on the right. When you see "5 out of 10" at the top of the picture, you have reached the passage i read about sit ups. ENJOY!
http://www.aolhealth.com/fitness/bad-exercises
Back pain lower right side causes are: Lower back and kidney disorders.
You could have a slipt disc in your lower back, they are very painful.
sciatica
There can be various reasons associated with this. Injuries, infections, fractured bone or tumor are some of them.
One can find information about the causes of lower back pain from the following sites; Chronic pain site, WebMD, Mayo clinic, Bupa, Health guide, and NHS.
LABOR
he herniated a disc (leaked disc fluid) between his L4-L5 in his lower back
Swollen feet are a condition in which muscles in the feet have an excessive fluid. This excessive fluid can be causes of increasing weight. It is also called Edema which usually affects the feet, lower legs and ankles.
The possible cause for a hard elongated lump on the lower back rib cage is infection. It can also be caused by shingles.
Starvation causes the plasma protein levels to decrease, and when there is less plasma protein in the blood, you get lower Po (Osmotic Pressure). Lower osmotic pressure means less pull (of tissue fluid) so this causes generalized edema.so basically, less plasma proteins -> decreased Po -> less pull -> reduced venous clearance --> fluid build up in tissue
Could be Kidney infection? Just a suggestion
appendix or kidney infection.