Once you have the offending foods removed and the gut has begun to heal, you have to start replenishing the good bugs. Everyone has bacteria and bugs living in their intestines. The trick is to get the right ratio. Most ASD kiddos have too many bad bugs in their system. We fought the yeastie beasties with Logan for many years. That is for another post though.
In this step, you must keep out the offending foods and add in high doses of probiotics. For Logan, I know we have reached our threshold when he gets loose stools. For him, it is similar to finding his threshold for Vitamin C. You keep increasing the dose until the stools get loose then you back down the dose.
Now, finding a good probiotic without dairy can be tricky. A lot of probiotics are made from dairy sources. There are dairy free ones out there. You simply have to look for them. So Delicious has come out with a whole line of coconut yogurts and kefirs that are great for putting in probiotics BUT the amount the child needs will require supplementation. Kirkmans and New Beginnings Nutritionals carry dairy free probiotics.
Of course, you have to do more research and learn more on your own. I am not a doctor nor do I play one on this blog. Dr. Buckley has not seen your child so this is generic advice. Always contact your own physician for questions. Just be forewarned that you may be better educated about these things than your doctor.