Did some late night, last minute-before-bed web searching on a topic that Max brought up and suddenly, I'm pretty sure I know what's wrong with me. This is a condition that explains everything I have been going through: Selective IgA Deficiency.
Of course, it sucks that there is no treatment for this condition, per se, you just have to treat the complications that come up because of it. Oh, and avoid blood transfusions because they can throw you into anaphylaxis. Also, it is hereditary, so I should have the kids tested if it turns out I have it.
DEFINITELY calling the dr's office with this particular question tomorrow morning first thing!