Hi Nate,

The good news is I don't think you have poison ivy.  It sounds to me like candida.  A bacterial overgrowth.  I'm not a doctor but I've seen and heard of this before.  Depending on how severe it is you may also have to take something internally as well.  Garlic is a good place to start.  Acidophillus to promote good bacteria and some kind of natural healing salve or powder for the underarms.  Check around at health food stores and specifically ask for this sort of item.  Good luck...