Please help!!! – Switch back to Nutramigen???

After bf didn’t work out due to serious supply issues I put my now 10wo Matthew on Nutramigen due to family history of milk intolerance (my older DS has autoimmune bowel disease that is exacerbated by food proteins, and he’s now on a dairy and gluten free diet). All was well with my LO until the reflux started up at ~3wks. We put him on Neocate nearly 3 weeks ago (he was ~7wks at the time) at the reco of my older DS’s GI doctor. At first it seemed like things were gong well, but then he got constipated, so bad that we had to put him on Lactulose. Within 3-4 days he was pooping normally, but it didn’t last long and now he’s backed up again. We gave him a glycerin suppository last night, which worked but not much came out.

Now since last night he’s hardly eating at all. He’s been taking only 2oz every 3 hours, and not even giving any strong hunger signs. It’s now nearly 8pm and he’s only had 14oz of formula today, whereas he usually takes ~25oz/day of Neocate (he had been eating ~30oz of Nutramigen). He also has bad gas that seems to hurt him (it will even wake him from his naps), and he’s been pulling up his legs in pain quite a bit today. My husband has a really bad cold and I suppose it’s possible the baby is not feeling well either, but he doesn’t have any typical cold symptoms.

The GI doc did not call me back today. I’m temped to switch Matthew back to Nutramigen because at least it seemed like less of a roller coaster. But why would he tolerate Nutramigen better tahn Neocate? They both have a substantial amount of corn syrup solids.