How does he go on gaviscon? DD was on losec for a bit and the plunket nurse recommended *supplementing* with gav when she really needed it. They act in different ways so can be used together, and a dose of gav often provided instant relief for her (just if she had too much she got constipated). We are mostly managing it via the diet now and just use gav as a back up if something I or she eats causes a prob.
With the dairy free you need to go completely DF not just avoiding milk etc.