She went to a good allergist today. The allergist's theory is that mono threw her immune system into overdrive. Then her body went nuts over the typhoid vaccine. The prednisone calmed it down, but when she went off it (and she did taper down), she had a rebound effect. So now she is going up to a higher dose, then tapering off very gradually, over a six week period. She goes back for a recheck just before finishing the lowest dose.
The doctor said that if she is ok after tapering off, they may never know whether her theory was correct or if it was something else. Which, to me, means carrying the epi-pen long-term, because who knows whether she may reacted to something that she seldom gets exposed to?