Still dealing with a rash

It's been two and a half weeks since I started breaking out in a rash from poison tree. The original spots are now healed (the skin is closed but it's a different color there), but I've been getting new spots: new ones on my arm, hands, knees, thighs, ankles... mostly extremities.

Then yesterday morning I woke up and discovered in horror that I had spots on my face, lips, belly button, butt, neck, back, chest, behind my ears, on my feet, and several new spots on my arms and legs. Holy crap. I looked like I had chicken pox with leprosy or something.

Prior to this I had been fighting my allergic reaction to urushiols with oral benadryl tablets and hydrocortisone cream. This prompted me to start the prednisone prescription that Jon brought with him (thanks Mom & Dad). After a bit of internet research, I think the new spots were mostly hives. My face cleared up within about 4 hours of taking the first dose of prednisone and my arms were cleared up in about 12. Thank god. Still, I worry about this because I've still got 8 weeks of field work to endure in an area full of poison tree with abundant mangos and cashews.

The sudden overnight appearance of so many new spots freaked Jon out because he's highly allergic to poison ivy too and I'd spent forever convincing him that I'd washed everything and I wasn't going to give it to him. As best I can tell, there are two main expanations for my sudden outburst of new spots :

-They were areas that were lightly exposed to oils from my backpack, clothes, or equipment that I spread to other places on my body by scratching my skin or while dressing.
-It was something I ate.

Both of these are possible, but I'm thinking it was probably something I ate. But what? Who knows. There are several possibilities.

-The spots on my lips could be from either the mango I ate on Sunday (I didn't touch the peel though) or the cashews I ate on Monday. I don't think they would cause the hives 3 or 4 days later, though.
-On Thursday night we ate dinner at an outdoor market. I've been 99.9% vegetarian for almost 8 years now, but on very rare occasions I eat meat. I decided that night to have a little bit of fish. I've never in my life eaten much fish. Perhaps that gave me hives?
-At the market I also ate some soup and I have no idea what was in it. Maybe the secret ingredient was mango peel?

Perhaps my body freaked out with hives because it's also covered in this rash. Maybe if the hives were from some kind of food, I wouldn't react to it under normal circumstances. I just really, really don't want to be fighting a rash for the next two months, and I know it's not a good idea to be on prednisone for that long.