Here I thought I was an anomaly having a baby with teenagers. 
Its good to know there is other people going through the same thing with low weight gain. We have been through this before with our youngest boy but he just gained weight slowly he did not actually loose weight. It makes me nervous because Liam has juvenile arthritis which I know went undiagnosed for years. He also has the gene for celiac disease. We actually thought he had the disease but he had testing done and it was another problem and then a short time later he had the genetic testing done.
I see you have older children with reflux. What do you do for them? My oldest has a heck of time with reflux especially when he gets sick.