I developed eczema over the last 6 months and I have hives, I went to an allergist, test is negative

I am 76 years old and in perfect health.  I developed eczema over the last 6 months and I have hives.  I went to an allergist and tested negative.  I take Zyrtec, 10 mg.  I break them in half and take them twice a day.  I keep developing hives.  I also have an anxiety problem.  Could that cause the Hives.  I also have an itchy scalp.  This all occurred over the last 6 months.  I'm at a loss.