Could mast cell disorder cause tachycardia no hypertension, chronic sinus problems, brain fog, sweating, fatigue, shortness of breath very high ige?

Yes: Yes to all the above, and you need to have a cardiac check up among other things. Depending on your location, you may need to go see experts in the field as ths is a rare disorder. Dr. Castells at brigham and women hosp in boston or dr lawrence schwartz in virginia.

Most common symptoms: Fatigue skin lesions (urticaria pigmentosa) and itching abdominal discomfort nausea and vomiting diarrhea food and drug intolerance olfactive intolerance infections (bronchitis, rhinitis, and conjunctivitis) ear/nose/throat inflammation anaphylaxis (shock from allergic or immune causes) episodes of very low blood pressure (including shock) and faintness.