Lots of testing :/

So our littlest guy has been struggling to gain weight--he has pretty bad reflux and was constantly spitting up.  We tried a couple different meds and prilosec seems to work ok.  He still spits up but not nearly as much and he has started gaining again but ssssllllloooooowwwwwwlllllllllyyyyyyy.  Because the older kids all have "stuff" going on, our current pediatrician ordered a bunch of tests to see if there are any of the "common" genetic causes going on, including the oh-so-fun sweat test (three and a half hours in the hospital for that one.  He was cooperative but his sweat glands were not so we had to do the test twice on one arm. Fun times).  So far, nothing much has turned up.  He has a few slightly off results on the blood work but not so far out of range they are really worried.  He has been voracious in his appetite lately, both for nursing and actual food so perhaps by his next appointment his weight will have caught up on its own :p