h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

This past summer and now into autumn my body's defense mechanisms have been on a constant red alert, even going haywire at times. Right now I'm ultrasensitive to several things, but I suspect that the real instigator is the molds and dust, to which I'm certifiably violently allergic. My one-level home has no attic or basement, and there is no such thing as a stucco exterior without a crack, according to those who know their stucco. My specialist broached the subject of allergy shots, but I'm having difficulty understanding the concept. Supposedly they inject you with the allergen to cause a reaction; then they try to calculate how many shots it will take over however long a period for your body to learn how to resist the allergen. The thing is, I'm getting the allergen at no cost from my house, so why should I buy the cow when I can get the milk for free?