Try a paperback by Claire Weekes called "Hope and Help for Your Nerves" . It was written over 20 yrs ago, but it is excellent and true to the heart. Weekes was an Australian psychiatrist that specialized in anxiety. Her writing is direct, and again, to the heart. Its in paperback and is pretty cheap. I believe her work was the send off to CBT.
The best thing to try is a therapy called CBT. They'll try to help you learn to think differently. Sometimes it works, sometimes it doesn't, but it should be tried. They should also teach relaxation techniques, such as meditation, exercise, and breathing exercises. As for natural remedies, start with a book called Natural Highs by Hyla Cass, a psychiatrist at UCLA. The natural medicine would usually combine something for anxiety directly such as an herbal relaxant like passionflower for systemic relaxation and something for short term relief such as kava or valerian or the like; perhaps something that affects serotonin, such as 5-HTP; and something for the adrenals, such as ashwagandha and holy basil. Diet might also be addressed. It's a complicated treatment, but it's a complicated problem.