C.M.
Hi... I went through this with one of my twins... His head was growing much faster than his brother... he also had a larger than average (although w/in range) fontenelle (soft spot)... I mean it was HUGE! And occasionally, I would notice that it was lumped up... as if fluid was pushing up through...
OMG... the scare is unreal... Ultrasounds... and yes, ultimately a CT... and NOTHING... the Dr. said he was quite normal... and that even the extra fluid on occasion was totally normal... although you don't generally see it... he even commented that the other twin actually had "small" head... jeez... thanks...
I know this is super scary... it was all I could do to keep from thowing up...
I also have a realative with a shunt... and although it totally sucks to have to have one... they aren't that bad... Just an FYI...
and IMHO... I don't think a tumor would make the skull grow... I would expect there to be pressure on the brain causing problems before the skull would grow a whole 3/4"...
In the end... you will feel better having the test as you will KNOW for sure there is nothing going on in there to be afraid of... rather than waiting until the next checkup to see if there is any noticable difference.
Hang in there...