About 3 months ago I had hives showing up on the insdie of my legs, arm pit area and behind the knees. (note I am a man and was working outside in a wooded Arkansas property). So I thought it could be something new I was allergic to, my primary care referred me to an allergist who did a large number of tests on my back. Outcome - no allergies. So they said try checking your thyroid. Again all blood tests are normal. No history of chronic hives in my family. It does seem that if I take Zyrtec the hives retrack/go away. But if I stop for 3-4 days then the hives return. What are my next steps to properly identify or diagnose what I have? Please help, frustrated....