I would push for it.. I just went back and re-read you lo's symptoms again.. although it is very cf, it is also Very allergy like.. When my dd was a baby she had fought the 1st 6 months with similar but not as extreme( since we caught it ) symptoms I thought it was milk , so I cut milk out, I tried soy.. still no good kept charting low and and getting sick and being always snooty to the point she was on a constant decongestants and awe were told to put prune juice in every bottle to help with the digestive issues.. turns out after many research from mommy I found she was allergic to milk but it was the whey not the lactose, which whey is in allot of things. Also those who so have milk allergies are actually at higher risk of havening sensitivities to soy.. so we switched her to goats milk and she was finally happy and stated to grow better and it was our savior... she still will get sick with it.. like when daddy forgot and put a little into her eggs the other day and she was trowing up all morning..... so see if you can get allergy testing or try to see your self if eliminating one at a time common allergens helps..