The Aromatherapy Organisations Council (aocuk.net) has a list of accredited full- and part-time courses - as part of an aromatherapy course, you would learn how to make essential oils out of plants. Neal's Yard Remedies (020-7498 1686) runs short, practical weekends away, harvesting herbs and making tinctures. For details of the herbal medicine diploma (three to five years) that would qualify you as a herbalist, call the National Institute of Medical Herbalists on 01392 426022. The University of Westminster School of Integrated Health (wmin.ac.uk) runs courses that cover all aspects of natural health, including aromatherapy and herbalism.

I was interested to read your article on blocked sinuses. I, too, have lost the sense of smell and taste for over 12 months. I have been on a dairy-free diet for nearly a year and have cut out bananas, oranges and yeast; I eat meat once or twice a week. I was prescribed antibiotics, after which I regained my sense of smell and taste for two weeks, and felt much better. I was in the south of France at the time, and the symptoms returned when I got home. I believe my immune system is poor and I take echinacea, vitamin C and zinc when I have cold symptoms. I have consulted a homeopath, but to no avail, and have resorted to Beconase to make life bearable, but I know I cannot continue to use it for too long.

Some detective work is in order. The question is, in France, did you feel better because of the antibiotics or because of the different surroundings? Your blocked sinuses could well be due to an allergic response to a food other than those you are avoiding, or to stimuli in your environment such as house dust mites, which weren't present in France. Call Brampton Scientific Services (01582 883014) for an allergy testing kit, which you can use with help from your GP. It may be possible to avoid the food, but not all allergens are avoidable. A natural antibiotic such as propolis contains more than 100 different compounds produced from tree sap by the honeybee, which all work to boost the immune system. It attacks viruses and bacteria, but leaves the body's friendly bacteria unharmed. Comvita Propolis and Honey Elixir (01730 813642, or comvita.com) will boost your defences and solve the sinus problem. Otherwise, try half a clove of garlic, crushed and eaten raw, followed by a sprig of parsley to absorb the smell. Take vitamin C (1,000mg) and zinc (15mg) twice a day, adding echinacea and carrot juice if exposed to a virus.

I suffer from painful mouth ulcers. How can I prevent or soothe them?

Mouth ulcers are caused by a minor viral infection and are a sign of being run down and under stress. Supplements of a vitamin B complex and 1,000mg a day of vitamin C, plus exercise and relaxation, will help. Try rinsing your mouth with a warm salt solution or cabbage juice. To combat the virus, add 15 drops of echinacea tincture (from Bioforce, 01294 277344) to a small amount of water, gargle and swill before swallowing. Repeat three times a day. Avoid smoking, chocolate, sweets, caffeine, walnuts, spicy foods and acidic foods such as citrus fruits, pineapple, strawberries and, yes, tomatoes. If ulcers last more than three weeks, see your GP - in very rare cases, they can be a sign of cancer.

· Emma Mitchell is a natural health therapist. Her recommendations are to be followed in conjunction with advice from your own healthcare provider. Send your questions to Wellbeing, Guardian Weekend, 119 Farringdon Road, London EC1R 3ER. Email: ask.emma@theguardian.com.