HI, MaryM ... Just saw this and wanted to add my experience, though not sure it will help, it might be something to consider. A little over two years ago (at Christmastime as well), I woke up with the same feeling ... a lump in my throat, and severe anxiety because of it. I finally got in to see a GP who did an EKG at my insistence (by this time I had chest heaviness as well, but I suspect that was the anxiety) and he told me he suspected acid reflux. I was in disbelief, as I never had anything remotely related to acid reflux, and was sure, again, due to my anxious nature, that it was something very serious (I had recently been exposed and had gotten sick from human parvovirus B19 and was sure it had wreaked havoc on my system).
Long story short, I went through 6 long months of doctor upon doctor, some well-meaning, and some just plain negligent (like the one who told me I had selective deficiency to parvovirus and I would eventually die from it). The symptoms that remained constant were the lump feeling in my throat, constant nausea (I could not eat anything and lost 15 pounds in a matter of weeks) and severe anxiety, which quickly led to sleeplessness and depression.
I had an endoscopy and they did not find anything, which caused me even more panic. In the end, I went back to the doctor I respected the most, who gave me this advice: stop seeing doctors, go on the OTC prilosec the original doctor had prescribed, and CHILL OUT! I did just that, and felt tremendously better within a couple of weeks, but not perfect. The doctor assured me that it may take a bit longer. Finally, after 6 weeks, I asked the doctor if I could come off of the meds ... I had no intention of being on prilosec for the rest of my life ... and he said yes. It has been 19 months now and I haven't taken a single antacid or had any symptom remotely resembling what I was experiencing. It was as if it were all a bad dream.
I write this here and now because I think there is just so much more that needs to be written and researched about the tremendous amount of anxiety we as parents and caregivers and our children must face when having to deal with LTFA on a daily basis. I had had a particularly tumultuous year, with both positive and negative events, and then we had to switch schools. We went from a completely loving and respectful community WRT food allergies, to a clueless and bullying atmosphere and it just pushed me over the edge. My doctor told me that I was so caught up in the constant fight or flight response, that it had made me completely unable to gain a healthy perspective on anything (i.e. why I refused to believe it was reflux vs. let's say, cancer).
Again, I am not sure if this will help, but if you find that you have not received answers from medical tests, perhaps you can continue to assess the role of anxiety in your daughter's life. Coincidentally, I came to the board tonight to see if I could find anything about anxiety, because my daughter came home last night from a night out at a gymnastics place and was in near hysterics because she was upset that kids were eating peanut snacks from the vending machine and returning to the equipment without washing their hands. She even found a wrapper in her cubbyhole. While I understand her concern, her reaction was a little extreme ... she was distraught, and it seemed to have come out of nowhere ... and I feel that she is dangling on that precipice of young adulthood, where she is realizing that she is going to have to take ultimate responsibility of her allergies, and she is not sure if she is ready or able to do so, hence the anxiety and emotion. That, and, of course, puberty!
Good luck to you. I hope you find the answers you are looking for. Our kids have so much on their plates, bless their hearts.