Hi, I think you do need to get him tested and checked out throughly - I can see your family history is worrying and it fits with the pattern of coeliac to have trouble gaining weight one solids are started. I agree with the nurse that getting some more meat into him would be a good idea, and some good fats and oils. Breastmilk is still the main game for him - maybe offer milk before solids feeds and anytime he is grizzly. It is not unusual for babies to swap percentiles up or down.