Many hugs to you Brimom.
Farmwife referred to EN - enteral nutrition. It's a special type of formula that is prescribed by the doctor and given either by NG tube, g-tube or mouth. If your child has not yet been placed on some kind of formula like this under the guidance of an experienced nutritionist then I would call and insist on a referral for this immediately. If not sooner.
Is she being screened by an allergist for food allergies? Did they distinguish between being lactose intolerant and having a milk protein allergy? This is particularly important because some of the EN formulas are lactose free but have milk protein.
I am going to assume she is being treated by a pediatric GI there in San Antonio either in private practice or affiliated with the Chidlren's Hospital.
It sounds like the workup is pretty good so far but I would not want a CT scan done if it could be avoided. Instead an MRE (a special MRI of the gut) would seem to me to be most appropriate given that a CT scan radiation dose is very high - perhaps as high as 500 xrays depending on the machine and procedure.
But MRE's are not done everywhere, especially on such a young child. It requires a specially trained radiologist and techs who have some special training as well. And I should qualify that by saying I have heard of others with young children who got MRE's but I think the youngest was at least 3 so it may not be an option with a toddler.
To be really honest, instead of going ahead with the CT scan, I think you should take your daughter ASAP for a consult at one of the two Pediatric IBD Consortium Programs in Texas. Texas Children's Hospital Pediatric IBD Center in Houston is probably closest. 832-822-3625 is their number. The other one is in Dallas, Dallas Children's Hospital Pediatric IBD Center 214-456-8000.
The number of very young children with IBD is tiny. Sadly, they are often very sick. A specialty center like Texas Children's or Dallas Children's sees many more IBD patients because they have special clinics and they see the most complex, unusual and difficult cases so they are likely to have seen and treated another child like yours before. This is a huge advantage. They are part of a network of ped IBD centers across the country and can consult with doctors at other even larger programs. Because they see so many IBD patients the radiology department has done many pediatric MRE's and is more likely to produce reliable and useful results.
So there's my speech about why you should be going to Houston or Dallas. If you had the resources I would say you should go even farther afield to Mayo Rochester, Cedar Sinai in LA, Cleveland Clinic or CHOP (Philly) since these are programs with stellar reputations and will have seen other children like yours because they see such a large number of pediatric IBD patients. CHOP sees around 4,000 a year.
If you're already getting care at either of those IBD clinic programs then I would strongly suggest you ask them why an MRE will not work instead of a CT scan.
All the best