Subbing as we're adopting from Ethiopia and trying to gather all the info I can. I just finished our training that talked quite a bit about parasites and also food issues, but since I don't have hands-on experience I'm hesitant to weigh in.
I'm so surprised your Ped only tested for Salmonella. According to our training the common parasites from there are tapeworms, flatworms, giardia (sp?), and such. The intestinal parasites especially would make you hungry constantly. I hope the CHOP has better answers for you.
Also, do you know what they served for food in Ethiopia? I saw a video of an orphanage over there and they were serving some sort of large tortilla thing. Also in our training was a story of a little Russian boy who had terrible food issues until someone fixed him black bread and borscht. Then he was ok and slowly transitioned after that.
I'm trying to picture myself in your shoes (as we will actually probably BE in your shoes in six months or so) and definitely reading all the suggestions and filing them away for future reference. I do understand your anguish, mama. Something is wrong with your little girl and you want desperately to fix it but you can't solve the puzzle. I hope you solve it soon and find people who can help you.