I have secondary MCAS, which comes with EDS. My tests were negative for primary, but still have it because of lovely body functions. Mine presents as what feels like year round allergies, constantly getting sick, sinus infections and ear infections frequently. Just lots of goo not pleasant. However my doctor put me on Cemetidine and a higher dose of Zyrtec and the whole world cleared it was amazing, I can think again the fog is gone and no longer have the constant allergy symptoms.