GL body Q&A.

I get pit stains. I shower daily and use strong deodorant. Yet, I have stains before second period. Help!

As if you don't have enough to worry about in puberty, right? Excessive sweating is called hyperhidrosis. According to guidelines from the International Hyperhidrosis Society, you know you have it if your sweating is embarrassing, depressing or prevents you from doing things. "Most people don't even tell their best friends," says Dr. Doris Day, spokesperson for the American Society for Dermatologic Surgery and a dermasurgeon in New York City. She recommends an over-the-counter product containing a deodorant and antiperspirant (try Certain Dri, $5.99, drugstore.com). If that doesn't work, a dermo can help you with this problem.

I'm 14, and my 12-year-old sister has gotten her period before me! What gives?

You and your sister each have your own DNA, and hers said she'd get her period first. Dr. Diane Merritt, director of pediatric and adolescent gynecology, Washington University School of Medicine, St. Louis, Mo., says, "The normal age for a first period is between 8 and 16." Genetics, general health and body weight are all determining factors. "As long as you see signs of normal development--height, breasts and pubic hair--do not worry," she says. Lots of girls are healthy late bloomers, but if you don't get yours by 16, head to a doc.

I have the worst lower back pain ever, and it hurts so bad when I pee. My friend thinks I could have a kidney stone! Is she right?

Lower back pain can be a symptom for lots of things, but problems with urination indicates that you may have kidney stones. These pesky little things are the build-up of crystallized salts and minerals in the urinary tract. Sometimes, they pass through when you pee ... but other times? Ouch! The tiny stones can cause serious ab and back pain, and make going to the bathroom a nightmare. Typically an adult problem, recent reports indicate they are occurring more frequently in kids. Drink lots of water, and cut down on sodium. Get to a doctor so he can give you a diagnosis.

I have a small, red bump near my nipple. Is it a pimple or something more serious?

Chances are, this is a Montgomery gland. All women have them on the areola, the area around the nipples, but they're not always noticeable. The glands, which look like goose bumps, lubricate and condition. Dr. Carie D'Agata says a gland could be blocked. "Try warm compresses," she suggests. If the bump is sore or is there for more than a month, see a gynecologist.