I'll try and keep this brief.... 
. DS, just 2 has always been a skinny little thing (Dad and I are slim). He dropped through the weight centiles quite quickly after his 1st birthday due to various bugs that winter. He was a refluxy baby and, to my dismay, has never been a good eater. He also poos at least 4 times a day, normally quickly after he has eaten. A very good day would be 3 poos, a bad day, maybe 6. I posted on here about 9 months ago very worried about his lack of weight gain and was told to seek advice re coeliac disease which I duly did. Upshot is we were referred and the blood tests, thank goodness, came back clear. We were discharged from the paed gastroenterologist as he had gained some weight over the summer with a hight fat diet and all was well. However the last few weeks he has gone backwards, eating very little and pooing frequently, often his stools are a pale colour. I dont know where to go next but still fell something isn't right. He seems to get bugs very easily but in all other ways is happy and developing normally...am I being over anxious and this is just the way he is or do I need to ask for more tests...if so...what?????