Q.I have been in therapy, in one form or another, for several years, trying to find out why I have such a problem handling stress and have so little control over my emotions. This morning, I realized that I was never taught to face responsibility. This may not be my only problem, but it's certainly a major one.

How can I make sure I teach this valuable lesson to our 13-year-old son? I realize I should have instilled this in him already, but . . .

Our son is a little lazy and has to be told to do something a few times before he does it. My husband is not home as much as I am and in our household it's more, "Mom, can I . . . ?" than "Dad, can I . . . ?" That's unfortunate because my husband has some fine qualities to teach our son.

I would very much appreciate suggestions and reading materials.

A.Having said that you have trouble accepting responsibility, you promptly accepted it for not teaching this attribute to your son. Don't be so hard on yourself. You're doing a much better job than you think.

Certainly there are many parents who would be amazed and delighted to get a 13-year-old to do what he is told after only a few reminders.

It's simply that there are certain ages at which both boys and girls are naturally slow to obey -- 2 and usually 4, 11 and the early teens. These are generally the years when children develop their self-esteem by seeing how independent they can be. It's not that they're standing up to their parents, they're standing up for themselves. The more these children are ordered about, the more they'll rebel.

You're seeing a little of this in your son, but not very much. As long as you let him talk about his ideas and his feelings -- so he knows he has the right to have those ideas and feelings -- he won't have to act them out. You seem to be striking a good balance.

As for your son turning to you more than he does to his dad -- that's typical, too, and probably as it should be. Children naturally ask permission of the parent who's primarily responsible for the day-to-day jobs at home. However, your husband could (and should) take part in the training process by taking your son camping or fishing or by inviting him on a short business trip. Time spent together will give them a chance to talk to each other, if only out of boredom.

Your own problem is much more pressing: You've made a big effort to handle stress and anxiety -- a very responsible thing to do -- and yet you haven't made much progress.

When symptoms are emotional you'll find that patients -- and doctors and the therapists -- usually assume that the illness is emotional, too. They may be right, and as long as you have these mood swings you'll need the support of a good psychotherapist.

But that's not all you need. It's time to look for a physical cause.

You should have a thorough work-up by an internist who is well-versed in the latest on matter over mind. Sometimes a chronic minor illness is so subtle the patient doesn't consult a medical doctor at all or it's so diffuse she goes to a series of them, looking for different answers to many small ailments.

The whole area of brain chemistry is exploding with new information and researchers are discovering thousands of ways that a malfunctioning body can affect the psyche. Now we know that a shortage of lithium or zinc can cause depression; that some dyes can cause hyperactivity; that allergies can cause mood changes, emotional instability and depression; and that a malabsorption of vitamins or amino acids can create mental problems.

Candida, for example, which attacks the immune system, is one recently discovered illness that is often overlooked and yet it's probably quite common. It involves an overgrowth of yeast in the body (or an allergic reaction to it) and can cause the patient to be tired or hyperactive, spacy, depressed, anxious, edgy and to have mild-to-serious mood swings. Headaches are another symptom and so are muscle or joint pains, numbness, ear problems, pre-menstrual syndrome, a low libido, constipation (or diarrhea), bladder infections, vaginitis, jock itch and athlete's foot. A candida patient can have some or most of these symptoms, triggered by something as innocuous as hormones, mold or carbohydrates. The greatest offenders, however, are antibiotics, cortisone and birth control pills, in that order, according to Washington candida expert Dr. James Brodsky.

The Yeast Connection, by pediatric allergist William G. Crook (available at $18 from Professional Books, Box 846, Jackson, Tenn. 38302, or send $3 for his booklet, "Yeast"), makes the candida story easy reading. And the March 1985 issue of Omni magazine has an excellent article on the subject.

Candida may not be the cause of your problem, but it is worth keeping in mind if you do decide to have a thorough medical examination. This is your life and your body. It's up to you to look for all the answers because you have the most at stake.