Q: I'm a 30-year-old single woman with endometriosis. For the past year I've had pain in different parts of my body -- back, rectum and pelvis. Sometimes my body feels like it's in spasm from pressure on a nerve. My doctor has been treating me with Danocrine, but it doesn't help much and he says I might want to consider more surgery. I'm not sure what to do.

A: Endometriosis is an uncommon and somewhat unusual condition affecting young women, in which tissue that normally lies inside the uterus is located outside the uterus, usually within the pelvis.

One theory is that this tissue, called the endometrium or "inner uterus," escapes the uterus through the fallopian tubes instead of being shed during a menstrual period. Once outside the uterus, this renegade tissue attaches to different pelvic structures, such as the rectum, various ligaments and major nerves. These nests of tissue can cause pain by irritation or pressure, so your sensation of "pressure on the nerve" is very valid. However, many women with endometriosis have no symptoms at all.

Because this tissue remains responsive to female hormones, symptoms tend to wax and wane with each menstrual cycle, though pain may also be constant.

There are several ways to treat endometriosis:

* Birth control pills work by lowering the amount of female hormones your body makes, decreasing the stimulation of endometrial tissue.

* Danocrine inhibits the activity of the pituitary gland and also reduces the estrogen-stimulation of endometrial tissue.

* Surgery is used to remove nests of endometrial tissue from sensitive, symptom-producing areas.

Interestingly enough, pregnancy often markedly reduces the amount of endometriosis, and usually has a lasting beneficial effect.

One of the difficulties about endometriosis is that its symptoms can be obscure and mistaken for other disorders. Another is that diagnosis usually requires directly seeing the implants of tissue, either through a laparoscope (a tube inserted into the abdomen under general anesthesia) or through an abdominal incision. You can't tell if you have endometriosis by a blood test or an X-ray, though a doctor may be able to make a tentative diagnosis by a history and physical examination.

If there is no question about your diagnosis, I'd suggest talking to your doctor about trying birth control pills or other hormonal therapy. Because you've already had surgery for this condition, I'd recommend getting a second opinion about the potential benefits of further surgery.

Q: What can be done about gas pain? It seems like every afternoon my stomach fills with trapped gas, and often gets bloated and uncomfortable. My doctor has suggested changes in diet and exercise. Do you have any other advice?

A: I'm alway a little hesitant to accept a diagnosis of "gas pain" at face value, because people have called everything from heart attacks to ulcers "gas pain." But assuming you've had some relatively benign stomach discomfort that hasn't changed much over a long period of time, and your doctor isn't suspicious about anything more serious, like colitis or gallstones, let me make a few comments about stomach bloating and gassiness.

One of the more common causes of stomach bloating is something called aerophagia, meaning air-swallowing. Some people unknowingly swallow sizable amounts of air while eating, drinking, chewing gum, smoking or sometimes during the swallowing we ordinarily do many times a day. For some people, air-swallowing represents a nervous habit, for others an unintentional nuisance. Stomach bloating and crampy pain also occur in people with:

* Lactose intolerance -- inability to readily absorb the milk-sugar (lactose) found in milk products.

* Irritable bowel syndrome -- intestinal spasms triggered by physical and psychologic factors.

* Other dietary factors -- certain foods (beans, legumes, onions, cabbage and bran, for example) and carbonated drinks may lead to increased intestinal gas.

In addition, some people seem to be more sensitive to the gas that's normally present in their intestines, without actually having increased amounts of gas.

I'd suggest talking with your doctor about the possibility of air-swallowing, and trying different dietary changes to see if eliminating any particular type of food would help. Eat foods slowly, and in a relaxed setting if possible. Chew them well and don't smoke or chew gum. An antacid with simethicone or anti-spasm medications to calm the intestines might also help.

Q: For two months I've had a constant, sometimes intense, burning sensation on the outside of my thigh. There is no redness, no rash and no tenderness -- just the burning. What could this be?

A. Sensations like these usually point to an mild nerve injury, in this case, the nerve that runs near the skin surface along the outer thigh.

This nerve is susceptible to minor trauma in the outer groin area, where it may be pinched by overlying muscles and ligaments.

Call meralgia paresthetica, this condition usually clears up by itself within a few months. Meralgia means thigh pain, and paresthetica refers to an abnormal sensation, such as a burning, prickling or tingling, or a sensation of something crawling on the skin.

For severe, persistent cases, you should see your doctor to make sure you don't have any unusual conditions -- a tumor in the pelvis, for example -- putting pressure on this nerve. If nothing is found, you can have minor surgery to relieve the pressure.