Taking Synthroid. Weight Gain, Hives And Swollen Face. Allergic To Synthroid? Have Low Cortisol Levels

I have been on synthroid for a year, continue to be worn out, gain weight and have multiple episodes of hives and facial swelling. One doctor upped my synthroid amount, another put me on the liquid, capsule form. And I reacted horribly to it with throat tightness and more hives. He now wants adrenal tests run because my cortisol levels are low, though I am very stressed and have been. The strangest part is that my hives started when I initially started synthroid, then stopped. Reappearing at the same time , one year later, during pollen season.
So confused.. Hypothyroid, allergy to synthroid, low cortisol levels, low vit D.. Combo of all. I don't know what to do.