I've been using a mixture of Claritin and Zyrtec for more than two years.  Here's my list to compare:

Morning:
200mg Gastrocrom
20mg Claritin
300mg Zantac
10mg Singulair

Evening:
200mg Gastrocrom
20mg Zyrtec
300mg Zantac
20mg Singulair

As needed (usually not):
50mg liquid Benadryl
10mg Pepcid Complete

All of my doctors know that I'm on this combination of medications and doses... my primary doctor, my local allergist, my hematologist... even Dr. Castells and Dr. Greenberger.  They're all totally fine with it.  In the winter I might drop my H1s back down to 10mg at a time (if I'm getting too dried out), but in the summer I really need 20mg/20mg.  Heat is a trigger for me... hot car, hot pavement... bleh.

Heather

My tryptase is normal too.  I have MCAD... anaphylaxis, angioedema, chronic urticaria... the whole nine yards.

I grew up in northern Wisconsin and take my kids there every summer for a few weeks.  One of our rituals is spending the day at the Mall of America.  My kids love the amusement park.   Last year was difficult!  The park has a glass atrium, so after about two hours... between the sun, the heat, walking around, standing in lines... I had to rent a cart to ride around in.  Otherwise, there's no way I could have made it through!  This year (thanks, I believe, to the increased Singulair)... totally different story.  We had such a good time!  I spent the whole day on the rides with my kids.  My son took a nap, but I didn't need one  

Anyway... I know the exhaustion you're talking about, but for most people there is hope.  Through medications, changes in my diet, and being careful about triggers I feel SO MUCH BETTER.  Keep looking for answers, even though with MCAD you might never get lab results to prove why you're feeling so awful.

Heather