I was multi-tasking searching the web for two topics, looking for GFCF recipes and looking for possible causes of Karston's abdominal pain.
From the GFCF recipe search, I ran across mention of a low oxalate diet (LOD) helping severe pediatric abdominal pain! Interesting! So I went looking for LOD and quickly got to the specific carbohydrate diet (SCD) (with recipes). Those might be worth trying, but it's so hard to get Karston to eat anything that I shudder to think about trying to get him to eat from an approved list. On the other hand, maybe tracking his diet for oxalates and carbs while tracking how he feels ...
I found this doctor, and he's not that far away either. Hmm, a specialist ... wouldn't be the first one, but we haven't gotten anywhere yet either.
I suspect either intestinal allergies (sadly, there's no test for these T-cell-mediated allergies, so you just have to associate symptoms with diet) or colitis. Since Cale was diagnosed with colitis and it can run in the family, I think it needs to be considered for Karston. Unfortunately, it looks like differential diagnosis is a current research topic, explaining why it's tough to get medical traction.
So, flipping through Pediatric Gastroenterology, I read up on Colitis and Short Stature. We already tested for Celiac Disease although he hadn't had any wheat that week (should be able test for any wheat in past six weeks, though). I read Cholecystitis, which is interesting since we were worried about possible bilirubin earlier this month (but we think it was artificial color from lollipops). I read Colic, linked to milk protein allergy, and found the differential diagnosis of soy protein intolerance interesting. However, colic weight gain is typical, which doesn't cover Karston falling off the weight charts at 6 months. I read about Crohn Disease (often considered with colitis) and other Malabsorption Syndromes. Protein Intolerance was interesting: "cow's milk proteins are most frequently implicated as a cause of food intolerance during infancy," "only a few of these [intolerances] have a clear allergic immunoglobulin E (IgE)–mediated pathogenesis" and "in children, GI symptoms are generally most common, with a frequency ranging from 50-80%, followed by cutaneous symptoms (20-40%), and respiratory symptoms (4-25%)." Constitutional Growth Delay mentions falling off the growth charts at 3-6 months of age, then resuming growth on the right slope but below the curve. Where have I seen that??? Silver-Russell Syndrome usually starts with low birthweight, which didn't happen. Oh, and your word of the day is borborygmus: tummy rumbles!; can be caused by "incomplete digestion of carbohydrate-containing foods including milk, gluten, fruits, vegetables, beans, legumes, and high-fiber whole grains."