There is a company called biocure that makes a supplement called ovamed (also known as TSO). It's milky and drinkable.
Are you ready for this? It's a suspension of pig whipworm eggs that your child would have to take every 3 weeks or so.
The eggs hatch, but they are the wrong kind of whipworm for humans, so they don't survive very long. They trigger the immune response but, and this is important, they do not trigger the AUTOimmune response. Very key.
This regimen is treating ulcerative colitis and crohn's disease in Europe (the company is German), has been used regularly by many people since 2004, and was in clinical trials in the USA last time I checked up on it. The FDA has not approved it yet for use in the USA, but it might be worth a trip to Germany to try it out!