Hello all. I have had a few babies like this there are several possibilities
here my top two are:
Over supply syndrome colic (we've stopped calling it overactive letdown
because mom's thought it was their fault)
Reflux
If the behavor occurs immediately after feeding (eg baby is ok until burping
or whenset down) the biggest suspect would be reflux.  I have a current client
who had her baby sleeping in the car seat at night because he would scream if
laid down. As long as he was upright with no pressure on his stomach he was
ok.
If there is no connection with feeding (eg the baby is fussy all the time,
investigate for over supply colic.
Off to work now
Marie Davis RN, IBCLC
Moreno Valley is hot (112 yesterday), steamy and trying to breathe through all
the smoke from brush fires in the area.