No allergies, but allergic reactions… do I have MCAS?

When spring comes, I feel like shit, get severe headaches, tight lungs, diharrea, tired AF, dry eyes, swollen sinuses, but somehow I’m not allergic! I’ve tried antihistamines and cortisone inhalers for 5 years. Always end up taking prednisolone just to survive. I went to an allergy specialist and he was like «I don’s suspect MCAS». I don’t believe him. What do you guys think