I know I sound like a broken record, but here goes.......

Do a thorough assessment to determine if there were ANY indications of
thrush/ predispositions for thrush  in mom (even prenatally), or baby
(early on).  Hx of antibiotics, vaginitis, "off/on" breastfeeding
behavior, ring around the rectum, fire-engine red diaper rash, etc.  The
gassiness goes without saying...I believe that increased gassiness IS
sometimes the only symptom of GI yeast infection, at least in the early
stages.   And, it is amazing what treating the yeast will do for
treating the reflux, colic, slow weight gain, etc.

I have seen babies, as young as 5 days of age (who were admitted to the
hospital for "vomiting", poor breastfeeding, etc.) with similar (and
other) problems which, when the "thrush" assessment was made, the picure
was complete.

Sandy Hess