Hi everyone I am new here. I have a 20 month old son who is failure to thrive and low birth weight. When he was a few months old his pedi did a sweat test on him and it came back negative for CF. Well since then he has been having trouble gaining weight. Just recently he has been dipping off the weight chart (he is at 3% for weight and 10% for height) I have to go back in two weeks for a weight check and they put him on Pediasure. He has had bronchitis, ear infections, colds, and twice he has had croup since he has been born. And just yesterday he has been having loose stools, and when we change him his stools smell really bad like burnt rubber (it is a very weird smell.) Does anyone here think that, this may warrant further testing for CF?