While you may not be "looking" for things to make you anxious or to add to your list of symptoms (at least not consciously), you ARE living anxiously. Yes, I know you say, often, that "I am not anxious and X happened". However as my signature says at the bottom of all my posts, MOST anxiety happens at the subconscious level. JUST because you don't feel consciously anxious or had a day or two of calm doesn't mean your mind & body are relaxed. It can take months of reduced anxiety before a body goes back to a more non-reactive state.
KM-- you are LIVING just like BEASTY (anxiety) wants you to. Your actions are driving you to feel this way.
I do understand that you're scared of the symptoms. You say you want to know "WHY?'' I am telling you why... you have an anxiety disorder. THIS is what it does to people. Ultimately allergies are not what caused this. Most anxiety disorders are a response to things going on in your life-----relationship issues,, financial issues, too many life stresses piling up on you at once. how one deals with such things often depends on how adequately you deal with LIFE. some people try to sweep things under the rug. which only works for so long before things start billowing out. some scream and shout but don't really solve anything. Some people, because of upbringing or life experiences or personality or trauma, haven't developed the problem solving skills necessary to work things out easily or adequately. However given time and stickwithedness people can come out the other side.
Bottom line, it isn't the allergies but something else that is at the core of your anxiety. You have mentioned that you had been agoraphobic. so you have a history of anxiety disorder. HA is just a new way that your mind is expressing anxiety. Some people can work their way out of things on their own and some need a good therapist (maybe with meds or maybe without). I don't know where you fall here. However I think with a sincere look at your life, you will find a few things that are at the core of your anxiety.
Finally: remember anxiety is a liar. that is what it does. the more we feed it---and you ARE feeding it by your actions and reactions and inaction--the more entrenched it gets.