Ok, 2yo settled

My 11 yo DS was dx with EE about 1 1/2y ago, through a routine upper GI scope that he has for his reflux. He ended up having to have an esophageal dilation with another scope because his esophagus was closing a little less than a year ago, but was asymptomatic for a while prior to that. He proably had EE for much longer, but was not picked up in the scopes (from the biopsies done) because he took just enough steroids off and on for asthma that he masked it. I, too, was very concerned about having to go the elemental formula/feeding tube route. But we did not have to.
We have a ped GI that we have seen for years, because of the severe reflux. He got scopes 1x a year routinely to monitor damage, etc. It was very hard to treat--at one point, he was taking 30mg prevacid 2x a day AND 4 dose of reglan per day and still had breakthrough because the damage was still slowly healing and so severe. We could not wean him off the reglan despite the black box warning of neuro problems, so he took it for about 5y

(label recommends no longer than 3m max). After the dilation, we went to a very good allergist who works with more difficult peds cases (she also treats my 2 yo who had to have scratch allergy testing at 15m due to life-threatening reactions). Allergy testing--it needs to be scratch, not bloodwork BTW, and to foods that they have been exposed to at least once, preferable recently, to avoid false positives--showed he was allergic to 33 foods and all environments and animals tested. We discussed elemental formula with her, and she said that she only treats that way as a last resort when everything else fails. It is difficult to stick with for a child who is already eating solid food, and yes, often results in a feeding tube to get enough nutrition. I will say that she is big into keeping reasonable normal life, and not going overboard unless necessary. So, for example my 2yo has lifethreatening egg allergies--she recc no vaxes, even the ones that don't contain egg ingredients, because of potential cross contamination issues. However, although the one with EE tested highly positive to dogs, she said we can have an indoor one with some precautions, and can do sleepovers at friends with dogs, take extra meds temporarily then, etc. So that give you an idea of her philosophy and approach.
So here is our game plan. DS continued his prevacid, at 15mg 2x a day. We added symbicort (contains flovent plus another med) 80 mg 1 puff 2x/day as he needed the combo for his undertreated asthma. Normally, it requires a swish and spit after dosing, but instead he swallows it because that is the protocol for EE. He also takes singulair 10mg once a day. It works to treat asthma/allergies by controlling eosinophils, and although it is experimental for EE, she said the research is really good, as is the anecdotal evidence, that it helps with EE a lot. At any rate, it also treated his asthma again, and helps with his environmental allergies. We are to avoid the 1 food he reacted very strongly to on the test, but he can eat the mild reactive ones, as the steroids, etc. control it well enough at this point (BUT no binging on reactive foods, keep in a reasonable rotation in his diet, avoid anything that seems to cause a problem that we notice). Her reasoning for not even attempting a full withdrawal, beside the fact that it was nearly all fruits and veggies and would be virtually impossible to maintain, was that he was reactive enough to the environmentals that we would have to do the steroids, etc. route anyway. He will continue to get regular scopes every couple of years, sooner if he feels his throat closing or he has trouble swallowing again, or if he develops a chronic unexplained cough again (his first symptom). After having had no luck weaning off the reglan for 5 years, he was able to wean down to nothing within weeks!!!
So, after that very long explanation, my recommendations are this: find a Ped GI AND a ped allergist who are experienced with treating EE AND that will work together to treat your child individually. Many allergists are not really familiar with this type of allergy, so do some research and call around. My guess is that if they did not suggest singulair they may not be up on the most current research, unless there is a reason to not use it in your child. FWIW, adding the singulair meant that for DS, his steroid dose is currently half of what would be expected to treat at his weight, and is controlling it well despite not pulling the foods. Also, short term, high dose prevacid or similar may be needed to heal the erosion and damage. I think DS ended up taking a very high dose for a few months, then tapering over a year or so (this was prior to the EE dx). At any rate, the treatment and maintenance dose will not necessarily be the same.
Good luck, and feel free to ask any questions. There is another mama who has dealt extensively with EE, USamma, I think. You may want to edit your title to reflect the EE dx.