Hi, Jenny, and welcome! I'm glad that you found us and joined the family.
I get periods where I'm more exhausted and I've been dizzy, too. Chompers asked if you are on any medication. If you are, google it and check the side effects. Many time that can be causing the problem. THEN, when you factor in anxiety, that makes any symptom a lot worse because we can conjure up the worst possible scenerios. Stress and anxiety just make anything worse.
Since you've been checked out several times, try to relax about it. When I was suffering from anxiety, I could take on the symptoms of many illnesses! I finally got a grip on the anxiety and I've been fine since. Anxiety could possibly be causing the nausea, weakness in the legs, as well as the clammy hands. I'm not a doctor but, since you've been checked out by one, this is my guess.
Be sure to read Fibro 101...the second thread on the forum. There are links to good information about fibro and you will learn a lot there. Read Symptoms and A Thorough Explanation of Fibromyalgia. These are good starting points for you.
I'm looking forward to getting to know you better. Don't hesitate to ask questions because we are here to help you. I hope to hear more from you soon.
Sherrine