This is kind of a complicated question because osteoarthritis and disc problems are very common, and are probably related more to your age than to your lupus. Osteoarthritis is the most common form of arthritis, and is caused by the loss of the cartilage that protects your joints, either through normal wear and tear, injury, or age. By age 25, about 12% of people will develop osteoarthritis in at least one joint, and the percentages go up as people get older. People who are overweight, or who have jobs that put a lot of stress on the joints, are at higher risk for developing osteoarthritis.
Degenerative disc disease is probably a bad term for doctors to use because it isn't really a disease - it's a normal consequence of getting older. Disks are the soft "cushions" between the bones of the spine that let you move your backbone - they also act as shock absorbers for your spine. As you get older, your discs become flatter -- less cushiony, and there is less space between your vertebra. This can show up on a x-ray, and it is what some doctors call "degenerative disc disease". Disc degeneration is a natural part of aging and over time all people will exhibit changes in their discs consistent with a greater or lesser degree of degeneration. In some people this can cause back pain - this varies a lot from person to person. DGD is usually treated with NSAIDs, sometimes muscle relaxers, and back exercises to improve mobility and strength. Although 2-3 days of bed rest may help during a period of acute back pain, prolonged bed rest is not a good idea and often makes the problem worse. Water aerobics, yoga and chiropractic care may all improve back pain.
If a disk becomes too weak, the outer part may tear. The inside part of the disk pushes through the tear - this is often referred to as a "herniated" or "ruptured" disc - if the protruding part of the disc presses on a nerve, this can cause pain, burning sensations, and sometimes weakness in one or both legs, depending on the location of the disc. A ruptured disc that causes paralysis or affects your bowel or bladder control is a medical emergency requiring surgery, but this is very rare. Most doctors will recommend that a ruptured disc be treated with medication, rest, physical therapy, and sometimes steroid injections - in most people, the disc will heal itself and the pain will resolve without surgery, usually in about a month. If there is significant nerve compression causing pain to radiate down the leg, or the pain persists for several weeks, doctors may recommend surgery to remove the disc. Most insurance companies require a trial of physical therapy before authorizing surgery. If the pain affects the back only, and doesn't radiate down the leg, surgery is of very little benefit and most doctors will not recommend it.
There are some newer treatments available including vax-d, and artificial disc replacement - these are best discussed with your doctor.
It is very difficult to get disability based on back conditions unless your only job experience has been manual labor involving lifting or carrying, or you have significant neurological involvement - if your treating doctor is not willing to support your claim for disability, it may be very difficult to get it.
Hope this helps - wish I could offer you some better answers.